Sorting algorithms/Selection sort
You are encouraged to solve this task according to the task description, using any language you may know.
Sorting Algorithm
This is a sorting algorithm. It may be applied to a set of data in order to sort it.
For comparing various sorts, see compare sorts.
For other sorting algorithms, see sorting algorithms, or:
Heap sort | Merge sort | Patience sort | Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort
- Task
Sort an array (or list) of elements using the Selection sort algorithm.
It works as follows:
First find the smallest element in the array and exchange it with the element in the first position, then find the second smallest element and exchange it with the element in the second position, and continue in this way until the entire array is sorted.
Its asymptotic complexity is O(n2) making it inefficient on large arrays.
Its primary purpose is for when writing data is very expensive (slow) when compared to reading, eg. writing to flash memory or EEPROM.
No other sorting algorithm has less data movement.
- References
- Rosetta Code: O (complexity).
- Wikipedia: Selection sort.
- Wikipedia: [Big O notation].
11l
<lang 11l>F selection_sort(&lst)
L(e) lst
V mn = min(L.index .< lst.len, key' x -> @lst[x])
(lst[L.index], lst[mn]) = (lst[mn], e)
V arr = [7, 6, 5, 9, 8, 4, 3, 1, 2, 0] selection_sort(&arr) print(arr)</lang>
- Output:
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
360 Assembly
The program uses ASM structured macros and two ASSIST macros to keep the code as short as possible. <lang 360asm>* Selection sort 26/06/2016 SELECSRT CSECT
USING SELECSRT,R13 base register
B 72(R15) skip savearea
DC 17F'0' savearea
STM R14,R12,12(R13) prolog
ST R13,4(R15) "
ST R15,8(R13) "
LR R13,R15 "
LA RJ,1 j=1
DO WHILE=(C,RJ,LE,N) do j=1 to n
LR RK,RJ k=j
LR R1,RJ j
SLA R1,2 .
LA R3,A-4(R1) @a(j)
L RT,0(R3) temp=a(j)
LA RI,1(RJ) i=j+1
DO WHILE=(C,RI,LE,N) do i=j+1 to n
LR R1,RI i
SLA R1,2 .
L R2,A-4(R1) a(i)
IF CR,RT,GT,R2 THEN if temp>a(i) then
LR RT,R2 temp=a(i)
LR RK,RI k=i
ENDIF , end if
LA RI,1(RI) i=i+1
ENDDO , end do
L R0,0(R3) a(j)
LR R1,RK k
SLA R1,2 .
ST R0,A-4(R1) a(k)=a(j)
ST RT,0(R3) a(j)=temp;
LA RJ,1(RJ) j=j+1
ENDDO , end do
LA R3,PG pgi=0
LA RI,1 i=1
DO WHILE=(C,RI,LE,N) do i=1 to n
LR R1,RI i
SLA R1,2 .
L R2,A-4(R1) a(i)
XDECO R2,XDEC edit a(i)
MVC 0(4,R3),XDEC+8 output a(i)
LA R3,4(R3) pgi=pgi+4
LA RI,1(RI) i=i+1
ENDDO , end do
XPRNT PG,L'PG print buffer
L R13,4(0,R13) epilog
LM R14,R12,12(R13) "
XR R15,R15 "
BR R14 exit
A DC F'4',F'65',F'2',F'-31',F'0',F'99',F'2',F'83',F'782',F'1'
DC F'45',F'82',F'69',F'82',F'104',F'58',F'88',F'112',F'89',F'74'
N DC A((N-A)/L'A) number of items of a PG DC CL80' ' buffer XDEC DS CL12 temp for xdeco
YREGS
RI EQU 6 i RJ EQU 7 j RK EQU 8 k RT EQU 9 temp
END SELECSRT</lang>
- Output:
-31 0 1 2 2 4 45 58 65 69 74 82 82 83 88 89 99 104 112 782
AArch64 Assembly
<lang AArch64 Assembly> /* ARM assembly AARCH64 Raspberry PI 3B */ /* program selectionSort64.s */
/*******************************************/ /* Constantes file */ /*******************************************/ /* for this file see task include a file in language AArch64 assembly */ .include "../includeConstantesARM64.inc"
/*********************************/ /* Initialized data */ /*********************************/ .data szMessSortOk: .asciz "Table sorted.\n" szMessSortNok: .asciz "Table not sorted !!!!!.\n" sMessResult: .asciz "Value : @ \n" szCarriageReturn: .asciz "\n"
.align 4
- TableNumber: .quad 1,3,6,2,5,9,10,8,4,7
TableNumber: .quad 10,9,8,7,6,5,4,3,2,1
.equ NBELEMENTS, (. - TableNumber) / 8
/*********************************/ /* UnInitialized data */ /*********************************/ .bss sZoneConv: .skip 24 /*********************************/ /* code section */ /*********************************/ .text .global main main: // entry of program
ldr x0,qAdrTableNumber // address number table mov x1,0 mov x2,NBELEMENTS // number of élements bl selectionSort ldr x0,qAdrTableNumber // address number table bl displayTable ldr x0,qAdrTableNumber // address number table mov x1,NBELEMENTS // number of élements bl isSorted // control sort cmp x0,1 // sorted ? beq 1f ldr x0,qAdrszMessSortNok // no !! error sort bl affichageMess b 100f
1: // yes
ldr x0,qAdrszMessSortOk bl affichageMess
100: // standard end of the program
mov x0,0 // return code mov x8,EXIT // request to exit program svc 0 // perform the system call
qAdrsZoneConv: .quad sZoneConv qAdrszCarriageReturn: .quad szCarriageReturn qAdrsMessResult: .quad sMessResult qAdrTableNumber: .quad TableNumber qAdrszMessSortOk: .quad szMessSortOk qAdrszMessSortNok: .quad szMessSortNok /******************************************************************/ /* control sorted table */ /******************************************************************/ /* x0 contains the address of table */ /* x1 contains the number of elements > 0 */ /* x0 return 0 if not sorted 1 if sorted */ isSorted:
stp x2,lr,[sp,-16]! // save registers stp x3,x4,[sp,-16]! // save registers mov x2,0 ldr x4,[x0,x2,lsl 3]
1:
add x2,x2,1 cmp x2,x1 bge 99f ldr x3,[x0,x2, lsl 3] cmp x3,x4 blt 98f mov x4,x3 b 1b
98:
mov x0,0 // not sorted b 100f
99:
mov x0,1 // sorted
100:
ldp x3,x4,[sp],16 // restaur 2 registers ldp x2,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
/******************************************************************/ /* selection sort */ /******************************************************************/ /* x0 contains the address of table */ /* x1 contains the first element */ /* x2 contains the number of element */ selectionSort:
stp x1,lr,[sp,-16]! // save registers stp x2,x3,[sp,-16]! // save registers stp x4,x5,[sp,-16]! // save registers stp x6,x7,[sp,-16]! // save registers mov x3,x1 // start index i sub x7,x2,1 // compute n - 1
1: // start loop
mov x4,x3 add x5,x3,1 // init index 2
2:
ldr x1,[x0,x4,lsl 3] // load value A[mini] ldr x6,[x0,x5,lsl 3] // load value A[j] cmp x6,x1 // compare value csel x4,x5,x4,lt // j -> mini add x5,x5,1 // increment index j cmp x5,x2 // end ? blt 2b // no -> loop cmp x4,x3 // mini <> j ? beq 3f // no ldr x1,[x0,x4,lsl 3] // yes swap A[i] A[mini] ldr x6,[x0,x3,lsl 3] str x1,[x0,x3,lsl 3] str x6,[x0,x4,lsl 3]
3:
add x3,x3,1 // increment i cmp x3,x7 // end ? blt 1b // no -> loop
100:
ldp x6,x7,[sp],16 // restaur 2 registers ldp x4,x5,[sp],16 // restaur 2 registers ldp x2,x3,[sp],16 // restaur 2 registers ldp x1,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
/******************************************************************/ /* Display table elements */ /******************************************************************/ /* x0 contains the address of table */ displayTable:
stp x1,lr,[sp,-16]! // save registers stp x2,x3,[sp,-16]! // save registers mov x2,x0 // table address mov x3,0
1: // loop display table
ldr x0,[x2,x3,lsl 3] ldr x1,qAdrsZoneConv bl conversion10 // décimal conversion ldr x0,qAdrsMessResult ldr x1,qAdrsZoneConv bl strInsertAtCharInc // insert result at @ character bl affichageMess // display message add x3,x3,1 cmp x3,NBELEMENTS - 1 ble 1b ldr x0,qAdrszCarriageReturn bl affichageMess
100:
ldp x2,x3,[sp],16 // restaur 2 registers ldp x1,lr,[sp],16 // restaur 2 registers ret // return to address lr x30
/********************************************************/ /* File Include fonctions */ /********************************************************/ /* for this file see task include a file in language AArch64 assembly */ .include "../includeARM64.inc" </lang>
ActionScript
<lang ActionScript>function selectionSort(input: Array):Array { //find the i'th element for (var i:uint = 0; i < input.length; i++) { //set minIndex to an arbitrary value var minIndex:uint=i; //find the smallest number for (var j:uint = i; j < input.length; j++) { if (input[j]<input[minIndex]) { minIndex=j; } } //swap the smallest number into place var tmp:Number=input[i]; input[i]=input[minIndex]; input[minIndex]=tmp; } return input; }</lang>
Ada
<lang ada>with Ada.Text_IO; use Ada.Text_IO;
procedure Test_Selection_Sort is
type Integer_Array is array (Positive range <>) of Integer;
procedure Sort (A : in out Integer_Array) is
Min : Positive;
Temp : Integer;
begin
for I in A'First..A'Last - 1 loop
Min := I;
for J in I + 1..A'Last loop
if A (Min) > A (J) then
Min := J;
end if;
end loop;
if Min /= I then
Temp := A (I);
A (I) := A (Min);
A (Min) := Temp;
end if;
end loop;
end Sort;
A : Integer_Array := (4, 9, 3, -2, 0, 7, -5, 1, 6, 8);
begin
Sort (A);
for I in A'Range loop
Put (Integer'Image (A (I)) & " ");
end loop;
end Test_Selection_Sort;</lang>
- Output:
-5 -2 0 1 3 4 6 7 8 9
ALGOL 68
<lang algol68>MODE DATA = REF CHAR;
PROC in place selection sort = (REF[]DATA a)VOID: BEGIN
INT min;
DATA temp;
FOR i FROM LWB a TO UPB a DO
min := i;
FOR j FROM i + 1 TO UPB a DO
IF a [min] > a [j] THEN
min := j
FI
OD;
IF min /= i THEN
temp := a [i];
a [i] := a [min];
a [min] := temp
FI
OD
END # in place selection sort #;
[32]CHAR data := "big fjords vex quick waltz nymph"; [UPB data]DATA ref data; FOR i TO UPB data DO ref data[i] := data[i] OD; in place selection sort(ref data); FOR i TO UPB ref data DO print(ref data[i]) OD; print(new line); print((data))</lang>
- Output:
abcdefghiijklmnopqrstuvwxyz big fjords vex quick waltz nymph
ARM Assembly
<lang ARM Assembly> /* ARM assembly Raspberry PI */ /* program selectionSort.s */
/************************************/ /* Constantes */ /************************************/ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ WRITE, 4 @ Linux syscall /*********************************/ /* Initialized data */ /*********************************/ .data szMessSortOk: .asciz "Table sorted.\n" szMessSortNok: .asciz "Table not sorted !!!!!.\n" sMessResult: .ascii "Value : " sMessValeur: .fill 11, 1, ' ' @ size => 11 szCarriageReturn: .asciz "\n"
.align 4 iGraine: .int 123456 .equ NBELEMENTS, 10
- TableNumber: .int 1,3,6,2,5,9,10,8,4,7
TableNumber: .int 10,9,8,7,6,5,4,3,2,1 /*********************************/ /* UnInitialized data */ /*********************************/ .bss /*********************************/ /* code section */ /*********************************/ .text .global main main: @ entry of program
1:
ldr r0,iAdrTableNumber @ address number table mov r1,#0 mov r2,#NBELEMENTS @ number of élements bl selectionSort ldr r0,iAdrTableNumber @ address number table bl displayTable ldr r0,iAdrTableNumber @ address number table mov r1,#NBELEMENTS @ number of élements bl isSorted @ control sort cmp r0,#1 @ sorted ? beq 2f ldr r0,iAdrszMessSortNok @ no !! error sort bl affichageMess b 100f
2: @ yes
ldr r0,iAdrszMessSortOk bl affichageMess
100: @ standard end of the program
mov r0, #0 @ return code mov r7, #EXIT @ request to exit program svc #0 @ perform the system call
iAdrsMessValeur: .int sMessValeur iAdrszCarriageReturn: .int szCarriageReturn iAdrsMessResult: .int sMessResult iAdrTableNumber: .int TableNumber iAdrszMessSortOk: .int szMessSortOk iAdrszMessSortNok: .int szMessSortNok /******************************************************************/ /* control sorted table */ /******************************************************************/ /* r0 contains the address of table */ /* r1 contains the number of elements > 0 */ /* r0 return 0 if not sorted 1 if sorted */ isSorted:
push {r2-r4,lr} @ save registers
mov r2,#0
ldr r4,[r0,r2,lsl #2]
1:
add r2,#1 cmp r2,r1 movge r0,#1 bge 100f ldr r3,[r0,r2, lsl #2] cmp r3,r4 movlt r0,#0 blt 100f mov r4,r3 b 1b
100:
pop {r2-r4,lr}
bx lr @ return
/******************************************************************/ /* selection sort */ /******************************************************************/ /* r0 contains the address of table */ /* r1 contains the first element */ /* r2 contains the number of element */ selectionSort:
push {r1-r7,lr} @ save registers
mov r3,r1 @ start index i
sub r7,r2,#1 @ compute n - 1
1: @ start loop
mov r4,r3 add r5,r3,#1 @ init index 2
2:
ldr r1,[r0,r4,lsl #2] @ load value A[mini] ldr r6,[r0,r5,lsl #2] @ load value A[j] cmp r6,r1 @ compare value movlt r4,r5 @ j -> mini add r5,#1 @ increment index j cmp r5,r2 @ end ? blt 2b @ no -> loop cmp r4,r3 @ mini <> j ? beq 3f @ no ldr r1,[r0,r4,lsl #2] @ yes swap A[i] A[mini] ldr r6,[r0,r3,lsl #2] str r1,[r0,r3,lsl #2] str r6,[r0,r4,lsl #2]
3:
add r3,#1 @ increment i cmp r3,r7 @ end ? blt 1b @ no -> loop
100:
pop {r1-r7,lr}
bx lr @ return
/******************************************************************/ /* Display table elements */ /******************************************************************/ /* r0 contains the address of table */ displayTable:
push {r0-r3,lr} @ save registers
mov r2,r0 @ table address
mov r3,#0
1: @ loop display table
ldr r0,[r2,r3,lsl #2] ldr r1,iAdrsMessValeur @ display value bl conversion10 @ call function ldr r0,iAdrsMessResult bl affichageMess @ display message add r3,#1 cmp r3,#NBELEMENTS - 1 ble 1b ldr r0,iAdrszCarriageReturn bl affichageMess
100:
pop {r0-r3,lr}
bx lr
/******************************************************************/ /* display text with size calculation */ /******************************************************************/ /* r0 contains the address of the message */ affichageMess:
push {r0,r1,r2,r7,lr} @ save registres
mov r2,#0 @ counter length
1: @ loop length calculation
ldrb r1,[r0,r2] @ read octet start position + index
cmp r1,#0 @ if 0 its over
addne r2,r2,#1 @ else add 1 in the length
bne 1b @ and loop
@ so here r2 contains the length of the message
mov r1,r0 @ address message in r1
mov r0,#STDOUT @ code to write to the standard output Linux
mov r7, #WRITE @ code call system "write"
svc #0 @ call systeme
pop {r0,r1,r2,r7,lr} @ restaur des 2 registres */
bx lr @ return
/******************************************************************/ /* Converting a register to a decimal unsigned */ /******************************************************************/ /* r0 contains value and r1 address area */ /* r0 return size of result (no zero final in area) */ /* area size => 11 bytes */ .equ LGZONECAL, 10 conversion10:
push {r1-r4,lr} @ save registers
mov r3,r1
mov r2,#LGZONECAL
1: @ start loop
bl divisionpar10U @ unsigned r0 <- dividende. quotient ->r0 reste -> r1
add r1,#48 @ digit
strb r1,[r3,r2] @ store digit on area
cmp r0,#0 @ stop if quotient = 0
subne r2,#1 @ else previous position
bne 1b @ and loop
@ and move digit from left of area
mov r4,#0
2:
ldrb r1,[r3,r2]
strb r1,[r3,r4]
add r2,#1
add r4,#1
cmp r2,#LGZONECAL
ble 2b
@ and move spaces in end on area
mov r0,r4 @ result length
mov r1,#' ' @ space
3:
strb r1,[r3,r4] @ store space in area add r4,#1 @ next position cmp r4,#LGZONECAL ble 3b @ loop if r4 <= area size
100:
pop {r1-r4,lr} @ restaur registres
bx lr @return
/***************************************************/ /* division par 10 unsigned */ /***************************************************/ /* r0 dividende */ /* r0 quotient */ /* r1 remainder */ divisionpar10U:
push {r2,r3,r4, lr}
mov r4,r0 @ save value
//mov r3,#0xCCCD @ r3 <- magic_number lower raspberry 3
//movt r3,#0xCCCC @ r3 <- magic_number higter raspberry 3
ldr r3,iMagicNumber @ r3 <- magic_number raspberry 1 2
umull r1, r2, r3, r0 @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0)
mov r0, r2, LSR #3 @ r2 <- r2 >> shift 3
add r2,r0,r0, lsl #2 @ r2 <- r0 * 5
sub r1,r4,r2, lsl #1 @ r1 <- r4 - (r2 * 2) = r4 - (r0 * 10)
pop {r2,r3,r4,lr}
bx lr @ leave function
iMagicNumber: .int 0xCCCCCCCD
</lang>
Arturo
<lang rebol>selectionSort: function [items][
sorted: new []
tmp: new items
while [not? empty? tmp][
minIndex: index tmp min tmp
'sorted ++ tmp\[minIndex]
remove 'tmp .index minIndex
]
return sorted
]
print selectionSort [3 1 2 8 5 7 9 4 6]</lang>
- Output:
1 2 3 4 5 6 7 8 9
AutoHotkey
ahk forum: discussion <lang AutoHotkey>MsgBox % SelecSort("") MsgBox % SelecSort("xxx") MsgBox % SelecSort("3,2,1") MsgBox % SelecSort("dog,000000,xx,cat,pile,abcde,1,cat,zz,xx,z")
SelecSort(var) { ; SORT COMMA SEPARATED LIST
StringSplit a, var, `, ; make array, size = a0
Loop % a0-1 {
i := A_Index, mn := a%i%, j := m := i
Loop % a0-i { ; find minimum
j++
If (a%j% < mn)
mn := a%j%, m := j
}
t := a%i%, a%i% := a%m%, a%m% := t ; swap first with minimum
}
Loop % a0 ; construct string from sorted array
sorted .= "," . a%A_Index%
Return SubStr(sorted,2) ; drop leading comma
}</lang>
AWK
<lang awk>function getminindex(gl, gi, gs) {
min = gl[gi]
gm = gi
for(gj=gi; gj <= gs; gj++) {
if ( gl[gj] < min ) {
min = gl[gj]
gm = gj
}
}
return gm
}
{
line[NR] = $0
} END { # sort it with selection sort
for(i=1; i <= NR; i++) {
mi = getminindex(line, i, NR)
t = line[i]
line[i] = line[mi];
line[mi] = t
}
#print it
for(i=1; i <= NR; i++) {
print line[i]
}
}</lang>
BBC BASIC
<lang BBCBASIC>DEF PROC_SelectionSort(Size%) FOR I% = 1 TO Size%-1
lowest% = I%
FOR J% = (I% + 1) TO Size%
IF data%(J%) < data%(lowest%) lowest% = J%
NEXT J%
IF I%<>lowest% SWAP data%(I%),data%(lowest%)
NEXT I% ENDPROC</lang>
BASIC
GWBASIC
Works with: QBASIC, QuickBASIC, VB-DOS <lang GWBASIC> 10 'SAVE"SELSORT",A 20 ' Selection Sort Algorithm 30 ' 40 ' VAR 50 DEFINT A-Z 60 OPTION BASE 1 70 I=0: J=0: IMINV = 0: IMAX = 0: TP! = 0: TL! = 0 80 ' 90 CLS 100 PRINT "This program does the Selection Sort Algorithm" 110 INPUT "Number of elements to sort (Max=1000, Enter=10)";IMAX 120 IF IMAX = 0 THEN IMAX = 10 130 IF IMAX > 1000 THEN IMAX = 1000 140 DIM N(IMAX) 150 ' Creates and shows the unsorted list 160 RANDOMIZE TIMER 170 FOR I=1 TO IMAX: N(I) = I: NEXT I 180 FOR I=1 TO IMAX 190 J = INT(RND*IMAX)+1 200 SWAP N(I), N(J) 210 NEXT I 220 PRINT: PRINT "Unsorted list:"; 230 FOR I=1 TO IMAX: PRINT N(I);: NEXT I 240 PRINT: PRINT 250 ' Sorts the list through the Selection Sort Algorithm and shows the results 260 TL! = TIMER 270 PRINT "Sorting"; IMAX; "numbers"; 280 COLOR 7+16: X = POS(0): PRINT"...";: COLOR 7 290 ITP = 0 300 FOR I=1 TO IMAX-1 310 IMINV = I 320 FOR J=I+1 TO IMAX 330 IF N(IMINV)>N(J) THEN IMINV = J 340 NEXT J 350 IF IMINV>I THEN SWAP N(IMINV), N(I): TP! = TP! + 1 360 NEXT I 370 LOCATE ,X: PRINT ". Done!" 380 PRINT: PRINT "Sorted list:"; 390 FOR I=1 TO IMAX: PRINT N(I);: NEXT I 400 ' Final results 410 PRINT: PRINT: PRINT "Numbers sorted:"; IMAX 420 PRINT "Total permutations done:";TP! 430 PRINT "Time lapse:"; TIMER-TL!; "seconds." 440 PRINT 450 PRINT "End of program" 460 END </lang>
C
<lang c>#include <stdio.h>
void selection_sort (int *a, int n) {
int i, j, m, t;
for (i = 0; i < n; i++) {
for (j = i, m = i; j < n; j++) {
if (a[j] < a[m]) {
m = j;
}
}
t = a[i];
a[i] = a[m];
a[m] = t;
}
}
int main () {
int a[] = {4, 65, 2, -31, 0, 99, 2, 83, 782, 1};
int n = sizeof a / sizeof a[0];
int i;
for (i = 0; i < n; i++)
printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
selection_sort(a, n);
for (i = 0; i < n; i++)
printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
return 0;
} </lang>
- Output:
4 65 2 -31 0 99 2 83 782 1 -31 0 1 2 2 4 65 83 99 782
C#
This is a generic implementation that works with any type that implements the IComparable interface
<lang csharp>class SelectionSort<T> where T : IComparable {
public T[] Sort(T[] list) {
int k;
T temp;
for (int i = 0; i < list.Length; i++) {
k = i;
for (int j=i + 1; j < list.Length; j++) {
if (list[j].CompareTo(list[k]) < 0) {
k = j;
}
}
temp = list[i];
list[i] = list[k];
list[k] = temp;
}
return list; }
}</lang>
Example of usage: <lang csharp>String[] str = { "this", "is", "a", "test", "of", "generic", "selection", "sort" };
SelectionSort<String> mySort = new SelectionSort<string>();
String[] result = mySort.Sort(str);
for (int i = 0; i < result.Length; i++) {
Console.WriteLine(result[i]);
}</lang>
- Output:
a generic is of selection sort test this
C++
Uses C++11. Compile with
g++ -std=c++11 selection.cpp
<lang cpp>#include <algorithm>
- include <iterator>
- include <iostream>
template<typename ForwardIterator> void selection_sort(ForwardIterator begin,
ForwardIterator end) {
for(auto i = begin; i != end; ++i) {
std::iter_swap(i, std::min_element(i, end));
}
}
int main() {
int a[] = {100, 2, 56, 200, -52, 3, 99, 33, 177, -199};
selection_sort(std::begin(a), std::end(a));
copy(std::begin(a), std::end(a), std::ostream_iterator<int>(std::cout, " "));
std::cout << "\n";
}</lang>
- Output:
-199 -52 2 3 33 56 99 100 177 200
Clojure
This is an implementation that mutates a Java arraylist in place.
<lang lisp>(import 'java.util.ArrayList)
(defn arr-swap! [#^ArrayList arr i j]
(let [t (.get arr i)]
(doto arr
(.set i (.get arr j))
(.set j t))))
(defn sel-sort!
([arr] (sel-sort! compare arr))
([cmp #^ArrayList arr]
(let [n (.size arr)]
(letfn [(move-min!
[start-i] (loop [i start-i] (when (< i n) (when (< (cmp (.get arr i) (.get arr start-i)) 0) (arr-swap! arr start-i i)) (recur (inc i)))))] (doseq [start-i (range (dec n))] (move-min! start-i)) arr))))</lang>
COBOL
<lang COBOL> PERFORM E-SELECTION VARYING WB-IX-1 FROM 1 BY 1
UNTIL WB-IX-1 = WC-SIZE.
...
E-SELECTION SECTION.
E-000.
SET WC-LOWEST TO WB-IX-1.
ADD 1 WC-LOWEST GIVING WC-START
PERFORM F-PASS VARYING WB-IX-2 FROM WC-START BY 1
UNTIL WB-IX-2 > WC-SIZE.
IF WB-IX-1 NOT = WC-LOWEST
MOVE WB-ENTRY(WC-LOWEST) TO WC-TEMP
MOVE WB-ENTRY(WB-IX-1) TO WB-ENTRY(WC-LOWEST)
MOVE WC-TEMP TO WB-ENTRY(WB-IX-1).
E-999.
EXIT.
F-PASS SECTION.
F-000.
IF WB-ENTRY(WB-IX-2) < WB-ENTRY(WC-LOWEST)
SET WC-LOWEST TO WB-IX-2.
F-999.
EXIT.</lang>
Common Lisp
<lang lisp>(defun selection-sort-vector (array predicate)
(do ((length (length array))
(i 0 (1+ i)))
((eql i length) array)
(do ((mindex i)
(min (aref array i))
(j i (1+ j)))
((eql j length)
(rotatef (aref array i) (aref array mindex)))
(when (funcall predicate (aref array j) min)
(setf min (aref array j)
mindex j)))))
(defun selection-sort-list (list predicate)
(flet ((min-first (list)
(do ((before-min nil)
(min (first list))
(prev list (rest prev))
(curr (rest list) (rest curr)))
((endp curr)
(if (null before-min) list
(let ((min (cdr before-min)))
(rplacd before-min (cdr min))
(rplacd min list)
min)))
(when (funcall predicate (first curr) min)
(setf before-min prev
min (first curr))))))
(let ((result (min-first list)))
(do ((head result (rest head)))
((endp (rest head)) result)
(rplacd head (min-first (rest head)))))))
(defun selection-sort (sequence predicate)
(etypecase sequence (list (selection-sort-list sequence predicate)) (vector (selection-sort-vector sequence predicate))))</lang>
Example use:
> (selection-sort (list 8 7 4 3 2 0 9 1 5 6) '<) (0 1 2 3 4 5 6 7 8 9) > (selection-sort (vector 8 7 4 3 2 0 9 1 5 6) '>) #(9 8 7 6 5 4 3 2 1 0)
Crystal
This sorts the array in-place. <lang crystal>def selectionSort(array : Array)
(0...array.size-1).each do |i|
nextMinIndex = i
(i+1...array.size).each do |j|
if array[j] < array[nextMinIndex]
nextMinIndex = j
end
end
if i != nextMinIndex
array.swap(i, nextMinIndex)
end
end
end</lang>
D
The actual function is very short. <lang d>import std.stdio, std.algorithm, std.array, std.traits;
enum AreSortableArrayItems(T) = isMutable!T &&
__traits(compiles, T.init < T.init) &&
!isNarrowString!(T[]);
void selectionSort(T)(T[] data) if (AreSortableArrayItems!T) {
foreach (immutable i, ref d; data)
data.drop(i).minPos[0].swap(d);
} unittest {
int[] a0; a0.selectionSort;
auto a1 = [1]; a1.selectionSort; assert(a1 == [1]);
auto a2 = ["a", "b"]; a2.selectionSort; assert(a2 == ["a", "b"]);
auto a3 = ["b", "a"]; a3.selectionSort; assert(a3 == ["a", "b"]);
auto a4 = ['a', 'b']; static assert(!__traits(compiles, a4.selectionSort));
dchar[] a5 = ['b', 'a']; a5.selectionSort; assert(a5 == "ab"d);
import std.typecons; alias Nullable!int N; auto a6 = [N(2), N(1)]; a6.selectionSort; // Not nothrow. assert(a6 == [N(1), N(2)]);
auto a7 = [1.0+0i, 2.0+0i]; // To be deprecated. static assert(!__traits(compiles, a7.selectionSort));
import std.complex; auto a8 = [complex(1), complex(2)]; static assert(!__traits(compiles, a8.selectionSort));
static struct F {
int x;
int opCmp(F f) { // Not pure.
return x < f.x ? -1 : (x > f.x ? 1 : 0);
}
}
auto a9 = [F(2), F(1)];
a9.selectionSort;
assert(a9 == [F(1), F(2)]);
}
void main() {
auto a = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3, 2]; a.selectionSort; a.writeln;
}</lang>
- Output:
[1, 1, 2, 2, 3, 3, 3, 4, 5, 5, 5, 6, 7, 8, 9, 9, 9]
Delphi
Array sort
Dynamic array is a 0-based array of variable length
Static array is an arbitrary-based array of fixed length <lang Delphi>program TestSelectionSort;
{$APPTYPE CONSOLE}
{.$DEFINE DYNARRAY} // remove '.' to compile with dynamic array
type
TItem = Integer; // declare ordinal type for array item
{$IFDEF DYNARRAY}
TArray = array of TItem; // dynamic array
{$ELSE}
TArray = array[0..15] of TItem; // static array
{$ENDIF}
procedure SelectionSort(var A: TArray); var
Item: TItem; I, J, M: Integer;
begin
for I:= Low(A) to High(A) - 1 do begin
M:= I;
for J:= I + 1 to High(A) do
if A[J] < A[M] then M:= J;
Item:= A[M];
A[M]:= A[I];
A[I]:= Item;
end;
end;
var
A: TArray; I: Integer;
begin {$IFDEF DYNARRAY}
SetLength(A, 16);
{$ENDIF}
for I:= Low(A) to High(A) do A[I]:= Random(100); for I:= Low(A) to High(A) do Write(A[I]:3); Writeln; SelectionSort(A); for I:= Low(A) to High(A) do Write(A[I]:3); Writeln; Readln;
end.</lang>
- Output:
0 3 86 20 27 67 31 16 37 42 8 47 7 84 5 29 0 3 5 7 8 16 20 27 29 31 37 42 47 67 84 86
String sort
// string is 1-based variable-length array of Char <lang Delphi>procedure SelectionSort(var S: string); var
Lowest: Char; I, J, M, L: Integer;
begin
L:= Length(S);
for I:= 1 to L - 1 do begin
M:= I;
for J:= I + 1 to L do
if S[J] < S[M] then M:= J;
Lowest:= S[M];
S[M]:= S[I];
S[I]:= Lowest;
end;
end;</lang>
// in : S = 'the quick brown fox jumps over the lazy dog' // out: S = ' abcdeeefghhijklmnoooopqrrsttuuvwxyz'
E
<lang e>def selectionSort := {
def cswap(c, a, b) {
def t := c[a]
c[a] := c[b]
c[b] := t
println(c)
}
def indexOfMin(array, first, last) {
var min := array[first]
var mini := first
for i in (first+1)..last {
if (array[i] < min) {
min := array[i]
mini := i
}
}
return mini
}
/** Selection sort (in-place). */
def selectionSort(array) {
def last := (array.size()-1)
for i in 0..(last - 1) {
cswap(array, i, indexOfMin(array, i + 1, last))
}
}
}</lang>
EasyLang
<lang>subr sort
for i = 0 to len data[] - 2
min_pos = i
for j = i + 1 to len data[] - 1
if data[j] < data[min_pos]
min_pos = j
.
.
swap data[i] data[min_pos]
.
. data[] = [ 29 4 72 44 55 26 27 77 92 5 ] call sort print data[]</lang>
EchoLisp
List sort
<lang scheme>
- recursive version (adapted from Racket)
(lib 'list) ;; list-delete (define (sel-sort xs (x0)) (cond [(null? xs) null] [else (set! x0 (apply min xs)) (cons x0 (sel-sort (list-delete xs x0)))]))
(sel-sort (shuffle (iota 13)))
→ (0 1 2 3 4 5 6 7 8 9 10 11 12)
- straightforward and more efficient implementation using list-swap!
(define (sel-sort list) (maplist (lambda( L) (first (list-swap! L (first L) (apply min L )))) list))
(sel-sort (shuffle (iota 13)))
→ (0 1 2 3 4 5 6 7 8 9 10 11 12)
</lang>
Array sort
<lang scheme>
- sort an array in place
(define (sel-sort a (amin) (imin)) (define ilast (1- (vector-length a))) (for [(i ilast)] (set! amin [a (setv! imin i)]) ;; imin := i , amin := a[imin] (for [(j (in-range (1+ i) (1+ ilast)))] (when (< [a j] amin) (set! amin [a (setv! imin j)]))) (vector-swap! a i imin)) a )
(define a #(9 8 2 6 3 5 4)) (sel-sort a)
→ #( 2 3 4 5 6 8 9)
</lang>
Eiffel
<lang Eiffel> class SELECTION_SORT [G -> COMPARABLE]
feature {NONE}
index_of_min (ar: ARRAY [G]; lower: INTEGER): INTEGER --Index of smallest element in 'ar' in the range of lower and the max index. require lower_positiv: lower >= 1 lower_in_range: lower <= ar.count ar_not_void: ar /= Void local i: INTEGER min: G do from i := lower min := ar.item (i) Result := i until i + 1 > ar.count loop if ar.item (i + 1) < min then min := ar.item (i + 1) Result := i + 1 end i := i + 1 end ensure result_is_set: Result /= Void end
sort (ar: ARRAY [G]): ARRAY [G] -- sort array ar with selectionsort require ar_not_void: ar /= Void local min_index: INTEGER ith: G do create Result.make_empty Result.deep_copy (ar) across Result as ic loop min_index := index_of_min (Result, ic.cursor_index) ith := Result [ic.cursor_index] Result [ic.cursor_index] := Result [min_index] Result [min_index] := ith end ensure Result_is_set: Result /= Void Result_sorted: is_sorted (Result) = True end
is_sorted (ar: ARRAY [G]): BOOLEAN --- Is 'ar' sorted in ascending order? require ar_not_empty: ar.is_empty = False local i: INTEGER do Result := True from i := ar.lower until i = ar.upper loop if ar [i] > ar [i + 1] then Result := False end i := i + 1 end end
feature
selectionsort (ar: ARRAY [G]): ARRAY [G] do Result := sort (ar) end
end </lang> Test: <lang eiffel> class APPLICATION
create make
feature
make do test := <<1, 27, 32, 99, 1, -7, 3, 5, 7>> io.put_string ("Unsorted: ") across test as ic loop io.put_string (ic.item.out + " ") end create selectionsort io.put_string ("%NSorted: ") test := selectionsort.selectionsort (test) across test as ar loop io.put_string (ar.item.out + " ") end end
test: ARRAY [INTEGER]
selectionsort: SELECTION_SORT [INTEGER]
end </lang>
- Output:
Unsorted: 1 27 32 99 1 -7 3 5 7 Sorted: -7 1 1 3 5 7 27 32 99
Elena
ELENA 5.0 : <lang elena>import extensions; import system'routines;
extension op {
selectionSort()
{
var copy := self.clone();
for(int i := 0, i < copy.Length, i += 1)
{
int k := i;
for(int j := i + 1, j < copy.Length, j += 1)
{
if (copy[j] < copy[k])
{
k := j
}
};
copy.exchange(i,k)
};
^ copy
}
}
public program() {
var list := new string[]{"this", "is", "a", "test", "of", "generic", "selection", "sort"};
console.printLine("before:",list.asEnumerable());
console.printLine("after:",list.selectionSort().asEnumerable())
}</lang>
- Output:
before:this,is,a,test,of,generic,selection,sort after:a,generic,is,of,selection,sort,test,this
Elixir
<lang elixir>defmodule Sort do
def selection_sort(list) when is_list(list), do: selection_sort(list, []) defp selection_sort([], sorted), do: sorted defp selection_sort(list, sorted) do max = Enum.max(list) selection_sort(List.delete(list, max), [max | sorted]) end
end</lang>
Example:
iex(10)> Sort.selection_sort([5,3,9,4,1,6,8,2,7]) [1, 2, 3, 4, 5, 6, 7, 8, 9]
Erlang
<lang Erlang> -module(solution). -import(lists,[delete/2,max/1]). -compile(export_all). selection_sort([],Sort)-> Sort; selection_sort(Ar,Sort)-> M=max(Ar), Ad=delete(M,Ar), selection_sort(Ad,[M|Sort]). print_array([])->ok; print_array([H|T])-> io:format("~p~n",[H]), print_array(T).
main()-> Ans=selection_sort([1,5,7,8,4,10],[]), print_array(Ans). </lang>
Euphoria
<lang euphoria>function selection_sort(sequence s)
object tmp
integer m
for i = 1 to length(s) do
m = i
for j = i+1 to length(s) do
if compare(s[j],s[m]) < 0 then
m = j
end if
end for
tmp = s[i]
s[i] = s[m]
s[m] = tmp
end for
return s
end function
include misc.e constant s = {4, 15, "delta", 2, -31, 0, "alfa", 19, "gamma", 2, 13, "beta", 782, 1}
puts(1,"Before: ") pretty_print(1,s,{2}) puts(1,"\nAfter: ") pretty_print(1,selection_sort(s),{2})</lang>
- Output:
Before: {
4,
15,
"delta",
2,
-31,
0,
"alfa",
19,
"gamma",
2,
13,
"beta",
782,
1
}
After: {
-31,
0,
1,
2,
2,
4,
13,
15,
19,
782,
"alfa",
"beta",
"delta",
"gamma"
}
F#
<lang fsharp> let rec ssort = function
[] -> []
| x::xs ->
let min, rest =
List.fold (fun (min,acc) x ->
if h<min then (h, min::acc)
else (min, h::acc))
(x, []) xs
in min::ssort rest
</lang>
Factor
<lang factor>USING: kernel math sequences sequences.extras ;
- select ( m n seq -- )
[ dup ] 2dip [ <slice> [ ] infimum-by* drop over + ] [ exchange ] bi ;
- selection-sort! ( seq -- seq' )
[ ] [ length dup ] [ ] tri [ select ] 2curry each-integer ;</lang>
Example use <lang factor>IN: scratchpad { 5 -6 3 9 -2 4 -1 -6 5 -5 } selection-sort!
--- Data stack: { -6 -6 -5 -2 -1 3 4 5 5 9 }</lang>
Forth
<lang forth>defer less? ' < is less?
- least ( start end -- least )
over cell+ do i @ over @ less? if drop i then cell +loop ;
- selection ( array len -- )
cells over + tuck ( end start end ) cell- swap do ( end ) i over least ( end least ) i @ over @ i ! swap ! cell +loop drop ;
create array 8 , 1 , 4 , 2 , 10 , 3 , 7 , 9 , 6 , 5 ,
array 10 selection array 10 cells dump</lang>
Fortran
<lang fortran>PROGRAM SELECTION
IMPLICIT NONE
INTEGER :: intArray(10) = (/ 4, 9, 3, -2, 0, 7, -5, 1, 6, 8 /) WRITE(*,"(A,10I5)") "Unsorted array:", intArray CALL Selection_sort(intArray) WRITE(*,"(A,10I5)") "Sorted array :", intArray
CONTAINS
SUBROUTINE Selection_sort(a) INTEGER, INTENT(IN OUT) :: a(:) INTEGER :: i, minIndex, temp
DO i = 1, SIZE(a)-1
minIndex = MINLOC(a(i:), 1) + i - 1
IF (a(i) > a(minIndex)) THEN
temp = a(i)
a(i) = a(minIndex)
a(minIndex) = temp
END IF
END DO
END SUBROUTINE Selection_sort
END PROGRAM SELECTION</lang>
- Output:
Unsorted array: 4 9 3 -2 0 7 -5 1 6 8 Sorted array : -5 -2 0 1 3 4 6 7 8 9
FreeBASIC
<lang freebasic>' version 03-12-2016 ' compile with: fbc -s console ' for boundry checks on array's compile with: fbc -s console -exx
Sub selectionsort(arr() As Long)
' sort from lower bound to the highter bound ' array's can have subscript range from -2147483648 to +2147483647
Dim As Long i, j, x Dim As Long lb = LBound(arr) Dim As Long ub = UBound(arr)
For i = lb To ub -1
x = i
For j = i +1 To ub
If arr(j) < arr(x) Then x = j
Next
If x <> i Then
Swap arr(i), arr(x)
End If
Next
End Sub
' ------=< MAIN >=------
Dim As Long i, array(-7 To 7) Dim As Long a = LBound(array), b = UBound(array)
Randomize Timer For i = a To b : array(i) = i : Next For i = a To b ' little shuffle
Swap array(i), array(Int(Rnd * (b - a +1)) + a)
Next
Print "unsort "; For i = a To b : Print Using "####"; array(i); : Next : Print selectionsort(array()) ' sort the array Print " sort "; For i = a To b : Print Using "####"; array(i); : Next : Print
' empty keyboard buffer While InKey <> "" : Wend Print : Print "hit any key to end program" Sleep End</lang>
- Output:
unsort 1 -7 -5 -4 6 5 -3 4 2 0 3 -6 -2 7 -1 sort -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Gambas
<lang gambas> siLow As Short = -99 'Set the lowest value number to create siHigh As Short = 99 'Set the highest value number to create siQty As Short = 20 'Set the quantity of numbers to create
Public Sub Main() Dim siToSort As Short[] = CreateNumbersToSort() Dim siPos, siLow, siChar, siCount As Short
PrintOut("To sort: ", siToSort)
For siCount = 0 To siToSort.Max
siChar = siCount For siPos = siCount + 1 To siToSort.Max If siToSort[siChar] > siToSort[siPos] Then siChar = siPos Next siLow = siToSort[siChar] siToSort.Delete(siChar, 1) siToSort.Add(siLow, siCount)
Next
PrintOut(" Sorted: ", siToSort)
End '--------------------------------------------------------- Public Sub PrintOut(sText As String, siToSort As String[]) Dim siCount As Short
Print sText;
For siCount = 0 To siToSort.Max
Print siToSort[siCount]; If siCount <> siToSort.max Then Print ", ";
Next
End '--------------------------------------------------------- Public Sub CreateNumbersToSort() As Short[] Dim siCount As Short Dim siList As New Short[]
For siCount = 0 To siQty
siList.Add(Rand(siLow, siHigh))
Next
Return siList
End</lang>
Output:
To sort: -11, -64, -20, -84, 94, -60, -82, -82, 37, -30, -75, 73, 19, -97, 81, -26, 55, 8, -15, -31, 36 Sorted: -97, -84, -82, -82, -75, -64, -60, -31, -30, -26, -20, -15, -11, 8, 19, 36, 37, 55, 73, 81, 94
GAP
<lang gap>SelectionSort := function(v)
local i, j, k, n, m;
n := Size(v);
for i in [1 .. n] do
k := i;
m := v[i];
for j in [i + 1 .. n] do
if v[j] < m then
k := j;
m := v[j];
fi;
od;
v[k] := v[i];
v[i] := m;
od;
end;
v := List([1 .. 100], n -> Random([1 .. 100])); SelectionSort(v); v;</lang>
Go
<lang go>package main
import "fmt"
var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
func main() {
fmt.Println("before:", a)
selectionSort(a)
fmt.Println("after: ", a)
}
func selectionSort(a []int) {
last := len(a) - 1
for i := 0; i < last; i++ {
aMin := a[i]
iMin := i
for j := i + 1; j < len(a); j++ {
if a[j] < aMin {
aMin = a[j]
iMin = j
}
}
a[i], a[iMin] = aMin, a[i]
}
}</lang>
More generic version that sorts anything that implements sort.Interface:
<lang go>package main
import (
"sort" "fmt"
)
var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
func main() {
fmt.Println("before:", a)
selectionSort(sort.IntSlice(a))
fmt.Println("after: ", a)
}
func selectionSort(a sort.Interface) {
last := a.Len() - 1
for i := 0; i < last; i++ {
iMin := i
for j := i + 1; j < a.Len(); j++ {
if a.Less(j, iMin) {
iMin = j
}
}
a.Swap(i, iMin)
}
}</lang>
Haskell
<lang haskell>import Data.List (delete)
selSort :: (Ord a) => [a] -> [a] selSort [] = [] selSort xs = selSort (delete x xs) ++ [x]
where x = maximum xs</lang>
Haxe
<lang haxe>class SelectionSort {
@:generic
public static function sort<T>(arr:Array<T>) {
var len = arr.length;
for (index in 0...len) {
var minIndex = index;
for (remainingIndex in (index+1)...len) {
if (Reflect.compare(arr[minIndex], arr[remainingIndex]) > 0)
minIndex = remainingIndex;
}
if (index != minIndex) {
var temp = arr[index];
arr[index] = arr[minIndex];
arr[minIndex] = temp;
}
}
}
}
class Main {
static function main() {
var integerArray = [1, 10, 2, 5, -1, 5, -19, 4, 23, 0];
var floatArray = [1.0, -3.2, 5.2, 10.8, -5.7, 7.3,
3.5, 0.0, -4.1, -9.5];
var stringArray = ['We', 'hold', 'these', 'truths', 'to',
'be', 'self-evident', 'that', 'all',
'men', 'are', 'created', 'equal'];
Sys.println('Unsorted Integers:' + integerArray);
SelectionSort.sort(integerArray);
Sys.println('Sorted Integers: ' + integerArray);
Sys.println('Unsorted Floats: ' + floatArray);
SelectionSort.sort(floatArray);
Sys.println('Sorted Floats: ' + floatArray);
Sys.println('Unsorted Strings: ' + stringArray);
SelectionSort.sort(stringArray);
Sys.println('Sorted Strings: ' + stringArray);
}
}</lang>
- Output:
Unsorted Integers: [1,10,2,5,-1,5,-19,4,23,0] Sorted Integers: [-19,-1,0,1,2,4,5,5,10,23] Unsorted Floats: [1,-3.2,5.2,10.8,-5.7,7.3,3.5,0,-4.1,-9.5] Sorted Floats: [-9.5,-5.7,-4.1,-3.2,0,1,3.5,5.2,7.3,10.8] Unsorted Strings: [We,hold,these,truths,to,be,self-evident,that,all,men,are,created,equal] Sorted Strings: [We,all,are,be,created,equal,hold,men,self-evident,that,these,to,truths]
Icon and Unicon
<lang Icon>procedure main() #: demonstrate various ways to sort a list and string
demosort(selectionsort,[3, 14, 1, 5, 9, 2, 6, 3],"qwerty")
end
procedure selectionsort(X,op) #: return sorted list ascending(or descending)
local i,m
op := sortop(op,X) # select how and what we sort
every i := 1 to *X-1 do {
m := i
every j := i + 1 to *X do
if op(X[j],X[m]) then m := j # find X that belongs @i low (or high)
X[m ~= i] :=: X[m]
}
return X
end</lang>
Note: This example relies on the supporting procedures 'sortop', and 'demosort' in Bubble Sort. The full demosort exercises the named sort of a list with op = "numeric", "string", ">>" (lexically gt, descending),">" (numerically gt, descending), a custom comparator, and also a string.
- Output:
Abbreviated sample
Sorting Demo using procedure selectionsort
on list : [ 3 14 1 5 9 2 6 3 ]
with op = &null: [ 1 2 3 3 5 6 9 14 ] (0 ms)
...
on string : "qwerty"
with op = &null: "eqrtwy" (0 ms)
Io
<lang io>List do (
selectionSortInPlace := method(
size repeat(idx,
swapIndices(idx, indexOf(slice(idx, size) min))
)
)
)
l := list(-1, 4, 2, -9) l selectionSortInPlace println # ==> list(-9, -1, 2, 4)</lang>
IS-BASIC
<lang IS-BASIC>100 PROGRAM "SelecSrt.bas" 110 RANDOMIZE 120 NUMERIC ARRAY(-5 TO 14) 130 CALL INIT(ARRAY) 140 CALL WRITE(ARRAY) 150 CALL SELECTIONSORT(ARRAY) 160 CALL WRITE(ARRAY) 170 DEF INIT(REF A) 180 FOR I=LBOUND(A) TO UBOUND(A) 190 LET A(I)=RND(98)+1 200 NEXT 210 END DEF 220 DEF WRITE(REF A) 230 FOR I=LBOUND(A) TO UBOUND(A) 240 PRINT A(I); 250 NEXT 260 PRINT 270 END DEF 280 DEF SELECTIONSORT(REF A) 290 FOR I=LBOUND(A) TO UBOUND(A)-1 300 LET MN=A(I):LET INDEX=I 310 FOR J=I+1 TO UBOUND(A) 320 IF MN>A(J) THEN LET MN=A(J):LET INDEX=J 330 NEXT 340 LET A(INDEX)=A(I):LET A(I)=MN 350 NEXT 360 END DEF</lang>
J
Create the following script and load it to a J session. <lang j>selectionSort=: verb define
data=. y
for_xyz. y do.
temp=. xyz_index }. data
nvidx=. xyz_index + temp i. <./ temp
data=. ((xyz_index, nvidx) { data) (nvidx, xyz_index) } data
end.
data
)</lang>
In an email discussion, Roger_Hui presented the following tacit code: <lang j>ix=: C.~ <@~.@(0, (i. <./)) ss1=: ({. , $:@}.)@ix^:(*@#)</lang>
To validate: <lang j> [data=. 6 15 19 12 14 19 0 17 0 14 6 15 19 12 14 19 0 17 0 14
selectionSort data
0 0 6 12 14 14 15 17 19 19
ss1 data
0 0 6 12 14 14 15 17 19 19</lang>
Java
This algorithm sorts in place. The call sort(array) will rearrange the array and not create a new one. <lang java>public static void sort(int[] nums){ for(int currentPlace = 0;currentPlace<nums.length-1;currentPlace++){ int smallest = Integer.MAX_VALUE; int smallestAt = currentPlace+1; for(int check = currentPlace; check<nums.length;check++){ if(nums[check]<smallest){ smallestAt = check; smallest = nums[check]; } } int temp = nums[currentPlace]; nums[currentPlace] = nums[smallestAt]; nums[smallestAt] = temp; } }</lang>
JavaScript
This algorithm sorts array of numbers. <lang javascript>function selectionSort(nums) {
var len = nums.length;
for(var i = 0; i < len; i++) {
var minAt = i;
for(var j = i + 1; j < len; j++) {
if(nums[j] < nums[minAt])
minAt = j;
}
if(minAt != i) {
var temp = nums[i];
nums[i] = nums[minAt];
nums[minAt] = temp;
}
}
return nums;
}</lang>
jq
The following implementation does not impose any restrictions on the types of entities that may appear in the array to be sorted. That is, the array may include any collection of JSON entities.
The definition also illustrates the use of an inner function (swap), and the use of jq's reduction operator, reduce.<lang jq># Sort any array def selection_sort:
def swap(i;j): if i == j then . else .[i] as $tmp | .[i] = .[j] | .[j] = $tmp end;
length as $length
| reduce range(0; $length) as $currentPlace
# state: $array
( .;
. as $array
| (reduce range( $currentPlace; $length) as $check
# state: [ smallestAt, smallest] except initially [null]
( [$currentPlace+1] ;
if length == 1 or $array[$check] < .[1]
then [$check, $array[$check] ]
else .
end
)) as $ans
| swap( $currentPlace; $ans[0] )
) ;</lang>Example:<lang jq>
[1, 3.3, null, 2, null, [1,{"a":1 }] ] | selection_sort </lang>
- Output:
[
null,
null,
1,
2,
3.3,
[
1,
{
"a": 1
}
]
]
Julia
<lang julia>function selectionsort!(arr::Vector{<:Real})
len = length(arr)
if len < 2 return arr end
for i in 1:len-1
lmin, j = findmin(arr[i+1:end])
if lmin < arr[i]
arr[i+j] = arr[i]
arr[i] = lmin
end
end
return arr
end
v = rand(-10:10, 10) println("# unordered: $v\n -> ordered: ", selectionsort!(v))</lang>
- Output:
# unordered: [2, -10, 0, -10, -9, -3, -3, 7, 8, -3] -> ordered: [-10, -10, -9, -3, -3, -3, 0, 2, 7, 8]
Kotlin
<lang scala>fun <T : Comparable<T>> Array<T>.selection_sort() {
for (i in 0..size - 2) {
var k = i
for (j in i + 1..size - 1)
if (this[j] < this[k])
k = j
if (k != i) {
val tmp = this[i]
this[i] = this[k]
this[k] = tmp
}
}
}
fun main(args: Array<String>) {
val i = arrayOf(4, 9, 3, -2, 0, 7, -5, 1, 6, 8) i.selection_sort() println(i.joinToString())
val s = Array(i.size, { -i[it].toShort() })
s.selection_sort()
println(s.joinToString())
val c = arrayOf('z', 'h', 'd', 'c', 'a')
c.selection_sort()
println(c.joinToString())
}</lang>
- Output:
-5, -2, 0, 1, 3, 4, 6, 7, 8, 9 -9, -8, -7, -6, -4, -3, -1, 0, 2, 5 a, c, d, h, z
Liberty BASIC
<lang lb> itemCount = 20
dim A(itemCount)
for i = 1 to itemCount
A(i) = int(rnd(1) * 100)
next i
print "Before Sort" gosub [printArray]
'--- Selection sort algorithm
for i = 1 to itemCount-1
jMin = i
for j = i+1 to itemCount
if A(j) < A(jMin) then jMin = j
next
tmp = A(i)
A(i) = A(jMin)
A(jMin) = tmp
next
'--- end of (Selection sort algorithm)
print "After Sort" gosub [printArray]
end
[printArray]
for i = 1 to itemCount
print using("###", A(i));
next i
print
return </lang>
LSE
<lang LSE> (*
- Tri par Sélection
- (LSE2000)
- )
PROCEDURE &Test(TABLEAU DE ENTIER pDonnees[], ENTIER pTaille) LOCAL pTaille
ENTIER i, j, minimum, tmp
POUR i <- 0 JUSQUA pTaille-1 FAIRE
minimum <- i
POUR j <- i+1 JUSQUA pTaille FAIRE
SI pDonnees[j] < pDonnees[minimum] ALORS
minimum <- j
FIN SI
BOUCLER
SI i # min ALORS
tmp <- pDonnees[i]
pDonnees[i] <- pDonnees[minimum]
pDonnees[minimum] <- tmp
FIN SI
BOUCLER
FIN PROCEDURE </lang>
Lua
<lang lua>function SelectionSort( f )
for k = 1, #f-1 do
local idx = k
for i = k+1, #f do
if f[i] < f[idx] then
idx = i
end
end
f[k], f[idx] = f[idx], f[k]
end
end
f = { 15, -3, 0, -1, 5, 4, 5, 20, -8 }
SelectionSort( f )
for i in next, f do
print( f[i] )
end</lang>
Maple
<lang Maple>arr:= Array([17,3,72,0,36,2,3,8,40,0]): len := numelems(arr): for i to len-1 do j_min := i: for j from i+1 to len do if arr[j] < arr[j_min] then j_min := j: end if: end do: if (not j_min = i) then temp := arr[i]: arr[i] := arr[j_min]: arr[j_min] := temp: end if: end do: arr;</lang>
- Output:
[0,0,2,3,3,8,17,36,40,72]
Mathematica
Procedural solution with custom min function:
<lang Mathematica>SelectSort[x_List] := Module[{n = 1, temp, xi = x, j},
While[n <= Length@x, temp = xin; For[j = n, j <= Length@x, j++, If[xij < temp, temp = xij]; ]; xin ;; = {temp}~Join~ Delete[xin ;;, First@Position[xin ;;, temp] ]; n++; ]; xi ]</lang>
Recursive solution using a pre-existing Min[] function:
<lang Mathematica>SelectSort2[x_List]:= Flatten[{Min@x, If[Length@x > 1, SelectSort2@Drop[x, First@Position[x, Min@x]], {}] }];</lang>
Validate by testing the ordering of a random number of randomly-sized random lists:
<lang Mathematica>{And @@ Table[l = RandomInteger[150, RandomInteger[1000]];
Through[And[Length@# == Length@SelectSort@# &, OrderedQ@SelectSort@# &]@l],
{RandomInteger[150]}],
Block[{$RecursionLimit = Infinity},
And @@ Table[l = RandomInteger[150, RandomInteger[1000]];
Through[And[Length@# == Length@SelectSort2@# &, OrderedQ@SelectSort2@# &]@l],
{RandomInteger[150]}]
]}</lang>
Validation Result:
{True, True}
MATLAB / Octave
<lang MATLAB>function list = selectionSort(list)
listSize = numel(list); for i = (1:listSize-1)
minElem = list(i);
minIndex = i;
%This for loop can be vectorized, but there will be no significant
%increase in sorting efficiency.
for j = (i:listSize)
if list(j) <= minElem
minElem = list(j);
minIndex = j;
end
end
if i ~= minIndex
list([minIndex i]) = list([i minIndex]); %Swap
end
end %for
end %selectionSort</lang>
Sample Usage: <lang MATLAB>>> selectionSort([4 3 1 5 6 2])
ans =
1 2 3 4 5 6</lang>
Maxima
<lang maxima>selection_sort(v) := block([k, m, n], n: length(v), for i: 1 thru n do (
k: i,
m: v[i],
for j: i + 1 thru n do
if v[j] < m then (k: j, m: v[j]),
v[k]: v[i],
v[i]: m
))$
v: makelist(random(199) - 99, i, 1, 10); /* [52, -85, 41, -70, -59, 88, 19, 80, 90, 44] */ selection_sort(v)$ v; /* [-85, -70, -59, 19, 41, 44, 52, 80, 88, 90] */</lang>
MAXScript
<lang maxscript>fn selectionSort arr = (
local min = undefined
for i in 1 to arr.count do
(
min = i
for j in i+1 to arr.count do
(
if arr[j] < arr[min] then
(
min = j
)
)
swap arr[i] arr[min]
)
arr
)
data = selectionSort #(4, 9, 3, -2, 0, 7, -5, 1, 6, 8) print data</lang>
N/t/roff
<lang N/t/roff>.de end .. .de array . nr \\$1.c 0 1 . de \\$1.push end . nr \\$1..\\\\n+[\\$1.c] \\\\$1 . end . de \\$1.pushln end . if \\\\n(.$>0 .\\$1.push \\\\$1 . if \\\\n(.$>1 \{ \ . shift . \\$1.pushln \\\\$@ . \} . end . de \\$1.dump end . nr i 0 1 . while \\\\n+i<=\\\\n[\\$1.c] .tm \\\\n[\\$1..\\\\ni] . rr i . end . de \\$1.swap end . if (\\\\$1<=\\\\n[\\$1.c])&(\\\\$2<=\\\\n[\\$1.c]) \{ \ . nr b \\\\n[\\$1..\\\\$1] . nr \\$1..\\\\$1 \\\\n[\\$1..\\\\$2] . nr \\$1..\\\\$2 \\\\nb . rr b . \} . end .. .array myArray .myArray.pushln 14 62 483 21 12 11 0 589 212 10 5 4 95 4 2 2 12 0 0 .de sort . nr i 0 1 . while \\n+i<=\\n[\\$1.c] \{ \ . nr j \\ni 1 . nr st \\nj . while \\n+j<=\\n[\\$1.c] \{ \ . if \\n[\\$1..\\nj]<\\n[\\$1..\\n(st] .nr st \\nj . \} . if !\\n(st=\\ni .\\$1.swap \\ni \\n(st . \} .. .sort myArray .myArray.dump</lang>
Output
<lang>0 0 0 2 2 4 4 5 10 11 12 12 14 21 62 95 212 483 589</lang>
Nanoquery
<lang Nanoquery>import math
def sort(nums) global math for currentPlace in range(0, len(nums) - 2) smallest = math.maxint smallestAt = currentPlace + 1 for check in range(currentPlace, len(nums) - 1) if nums[check] < smallest smallestAt = check smallest = nums[check] end end temp = nums[currentPlace] nums[currentPlace] = nums[smallestAt] nums[smallestAt] = temp end return nums end</lang>
Nemerle
<lang Nemerle>using System; using System.Console;
module Selection {
public static Sort[T](this a : array[T]) : void
where T : IComparable
{
mutable k = 0;
def lastindex = a.Length - 1;
foreach (i in [0 .. lastindex])
{
k = i;
foreach (j in [i .. lastindex])
when (a[j].CompareTo(a[k]) < 0) k = j;
a[i] <-> a[k];
}
}
Main() : void
{
def arr = array[6, 2, 8, 3, 9, 4, 7, 3, 9, 1];
arr.Sort();
foreach (i in arr) Write($"$i ");
}
}</lang>
NetRexx
<lang NetRexx>/* NetRexx */ options replace format comments java crossref savelog symbols binary
import java.util.List
placesList = [String -
"UK London", "US New York", "US Boston", "US Washington" - , "UK Washington", "US Birmingham", "UK Birmingham", "UK Boston" -
]
lists = [ -
placesList - , selectionSort(String[] Arrays.copyOf(placesList, placesList.length)) -
]
loop ln = 0 to lists.length - 1
cl = lists[ln] loop ct = 0 to cl.length - 1 say cl[ct] end ct say end ln
return
method selectionSort(a = String[]) public constant binary returns String[]
rl = String[a.length] al = List selectionSort(Arrays.asList(a)) al.toArray(rl)
return rl
method selectionSort(a = List) public constant binary returns ArrayList
ra = ArrayList(a) n = ra.size
iPos = int iMin = int
loop iPos = 0 to n - 1
iMin = iPos
loop i_ = iPos + 1 to n - 1
if (Comparable ra.get(i_)).compareTo(Comparable ra.get(iMin)) < 0 then do
iMin = i_
end
end i_
if iMin \= iPos then do
swap = ra.get(iPos)
ra.set(iPos, ra.get(iMin))
ra.set(iMin, swap)
end
end iPos
return ra
</lang>
- Output:
UK London US New York US Boston US Washington UK Washington US Birmingham UK Birmingham UK Boston UK Birmingham UK Boston UK London UK Washington US Birmingham US Boston US New York US Washington
Nim
<lang nim>proc selectionSort[T](a: var openarray[T]) =
let n = a.len
for i in 0 ..< n:
var m = i
for j in i ..< n:
if a[j] < a[m]:
m = j
swap a[i], a[m]
var a = @[4, 65, 2, -31, 0, 99, 2, 83, 782] selectionSort a echo a</lang>
- Output:
@[-31, 0, 2, 2, 4, 65, 83, 99, 782]
OCaml
<lang ocaml>let rec selection_sort = function
[] -> []
| first::lst ->
let rec select_r small output = function
[] -> small :: selection_sort output
| x::xs when x < small -> select_r x (small::output) xs
| x::xs -> select_r small (x::output) xs
in
select_r first [] lst</lang>
Oforth
<lang Oforth>: selectSort(l) | b j i k s |
l size ->s l asListBuffer ->b
s loop: i [
i dup ->k b at
i 1 + s for: j [ b at(j) 2dup <= ifTrue: [ drop ] else: [ nip j ->k ] ]
k i b at b put i swap b put
]
b dup freeze ;</lang>
ooRexx
<lang oorexx>/*REXX ****************************************************************
- program sorts an array using the selection-sort method.
- derived from REXX solution
- Note that ooRexx can process Elements of the stem argument (Use Arg)
- 06.10.2010 Walter Pachl
- /
call generate /*generate the array elements. */ call show 'before sort' /*show the before array elements,*/ call selectionSort x. /*invoke the selection sort. */ call show 'after sort' /*show the after array elements.*/ exit /*stick a fork in it, we're done.*/
selectionSort: Procedure
Use Arg s. /* gain access to the argument */
do j=1 To s.0-1
t=s.j;
p=j;
do k=j+1 to s.0
if s.k<t then do;
t=s.k;
p=k;
end
end
if p=j then
iterate
t=s.j;
s.j=s.p;
s.p=t
end
return
show:
Parse Arg heading
Say heading
Do i=1 To x.0
Say i' 'x.i
End
say copies('-',79)
Return
return
generate:
x.1='---The seven hills of Rome:---' x.2='==============================' x.3='Caelian' x.4='Palatine' x.5='Capitoline' x.6='Virminal' x.7='Esquiline' x.8='Quirinal' x.9='Aventine' x.0=9 return</lang>
Oz
Although lists are much more used in Oz than arrays, this algorithm seems more natural for arrays. <lang oz>declare
proc {SelectionSort Arr}
proc {Swap K L}
Arr.K := (Arr.L := Arr.K)
end
Low = {Array.low Arr}
High = {Array.high Arr}
in
%% for every index I of the array
for I in Low..High do
%% find the index of the minimum element %% with an index >= I Min = {NewCell Arr.I}
MinIndex = {NewCell I}
in
for J in I..High do
if Arr.J < @Min then
Min := Arr.J MinIndex := J
end
end %% and put that minimum element to the left {Swap @MinIndex I}
end
end
A = {Tuple.toArray unit(3 1 4 1 5 9 2 6 5)}
in
{SelectionSort A}
{Show {Array.toRecord unit A}}</lang>
PARI/GP
<lang parigp>selectionSort(v)={
for(i=1,#v-1,
my(mn=i,t);
for(j=i+1,#v,
if(v[j]<v[mn],mn=j)
);
t=v[mn];
v[mn]=v[i];
v[i]=t
);
v
};</lang>
Pascal
See Delphi
Perl
<lang perl>sub selection_sort
{my @a = @_;
foreach my $i (0 .. $#a - 1)
{my $min = $i + 1;
$a[$_] < $a[$min] and $min = $_ foreach $min .. $#a;
$a[$i] > $a[$min] and @a[$i, $min] = @a[$min, $i];}
return @a;}</lang>
Phix
with javascript_semantics function selection_sort(sequence s) for i=1 to length(s) do integer m = i object si = s[i], sm = s[m] for j=i+1 to length(s) do object sj = s[j] if sj<sm then {sm,m} = {sj,j} end if end for if sm<si then s[i] = sm s[m] = si end if end for return s end function ?selection_sort(shuffle(tagset(10)))
- Output:
{1,2,3,4,5,6,7,8,9,10}
PHP
Iterative: <lang php>function selection_sort(&$arr) {
$n = count($arr);
for($i = 0; $i < count($arr); $i++) {
$min = $i;
for($j = $i + 1; $j < $n; $j++){
if($arr[$j] < $arr[$min]){
$min = $j;
}
}
list($arr[$i],$arr[$min]) = array($arr[$min],$arr[$i]);
}
}</lang> Recursive: <lang php>function selectionsort($arr,$result=array()){
if(count($arr) == 0){
return $result;
}
$nresult = $result;
$nresult[] = min($arr);
unset($arr[array_search(min($arr),$arr)]);
return selectionsort($arr,$nresult);
}</lang>
PicoLisp
<lang PicoLisp>(de selectionSort (Lst)
(map
'((L) (and (cdr L) (xchg L (member (apply min @) L))))
Lst )
Lst )</lang>
PL/I
<lang PL/I> Selection: procedure options (main); /* 2 November 2013 */
declare a(10) fixed binary initial (
5, 7, 3, 98, 4, -3, 25, 20, 60, 17);
put edit (trim(a)) (a, x(1));
call Selection_Sort (a);
put skip edit (trim(a)) (a, x(1));
Selection_sort: procedure (a);
declare a(*) fixed binary; declare t fixed binary; declare n fixed binary; declare (i, j, k) fixed binary;
n = hbound(a,1);
do j = 1 to n;
k = j; t = a(j);
do i = j+1 to n;
if t > a(i) then do; t = a(i); k = i; end;
end;
a(k) = a(j); a(j) = t;
end;
end Selection_Sort;
end Selection; </lang> Results:
5 7 3 98 4 -3 25 20 60 17 -3 3 4 5 7 17 20 25 60 98
PowerShell
<lang PowerShell>Function SelectionSort( [Array] $data ) { $datal=$data.length-1 0..( $datal - 1 ) | ForEach-Object { $min = $data[ $_ ] $mini = $_ ( $_ + 1 )..$datal | ForEach-Object { if( $data[ $_ ] -lt $min ) { $min = $data[ $_ ] $mini = $_ } } $temp = $data[ $_ ] $data[ $_ ] = $min $data[ $mini ] = $temp } $data }
$l = 100; SelectionSort( ( 1..$l | ForEach-Object { $Rand = New-Object Random }{ $Rand.Next( 0, $l - 1 ) } ) )</lang>
Prolog
Works with SWI-Prolog 6.3.11 (needs nth0/4). <lang Prolog> selection_sort([], []). selection_sort([H | L], [H1 | L2]) :- exchange(H, L, H1, L1), selection_sort(L1, L2).
exchange(H, [], H, []).
exchange(H, L, H1, L1) :- min_list(L, H2), ( H < H2 -> H1 = H, L1 = L ; H1 = H2, % does the exchange of the number H % and the min of the list nth0(Ind, L, H1, L2), nth0(Ind, L1, H, L2)). </lang>
PureBasic
<lang PureBasic>Procedure selectionSort(Array a(1))
Protected i, j, lastIndex, minIndex
lastIndex = ArraySize(a())
For i = 0 To lastIndex - 1
minIndex = i
For j = i + 1 To lastIndex
If a(minIndex) > a(j)
minIndex = j
EndIf
Next
Swap a(minIndex), a(i)
Next
EndProcedure</lang>
Python
<lang python>def selection_sort(lst):
for i, e in enumerate(lst):
mn = min(range(i,len(lst)), key=lst.__getitem__)
lst[i], lst[mn] = lst[mn], e
return lst</lang>
Qi
<lang qi>(define select-r
Small [] Output -> [Small | (selection-sort Output)] Small [X|Xs] Output -> (select-r X Xs [Small|Output]) where (< X Small) Small [X|Xs] Output -> (select-r Small Xs [X|Output]))
(define selection-sort
[] -> [] [First|Lst] -> (select-r First Lst []))
(selection-sort [8 7 4 3 2 0 9 1 5 6]) </lang>
Quackery
<lang Quackery> [ 0 swap
behead swap
witheach
[ 2dup > iff
[ nip nip
i^ 1+ swap ]
else drop ]
drop ] is least ( [ --> n )
[ [] swap
dup size times
[ dup least pluck
swap dip join ]
drop ] is ssort ( [ --> [ )
[] 20 times [ 10 random join ] dup echo cr ssort echo cr</lang>
- Output:
[ 5 2 5 0 4 5 1 5 1 1 0 3 7 2 0 9 6 1 8 7 ] [ 0 0 0 1 1 1 1 2 2 3 4 5 5 5 5 6 7 7 8 9 ]
R
For loop: <lang r>selectionsort.loop <- function(x) {
lenx <- length(x)
for(i in seq_along(x))
{
mini <- (i - 1) + which.min(x[i:lenx])
start_ <- seq_len(i-1)
x <- c(x[start_], x[mini], x[-c(start_, mini)])
}
x
}</lang> Recursive:
(A prettier solution, but, you may need to increase the value of options("expressions") to test it. Also, you may get a stack overflow if the length of the input vector is more than a few thousand.) <lang r>selectionsort.rec <- function(x) {
if(length(x) > 1)
{
mini <- which.min(x)
c(x[mini], selectionsort(x[-mini]))
} else x
}</lang>
Ra
<lang Ra> class SelectionSort **Sort a list with the Selection Sort algorithm**
on start
args := program arguments .sort(args) print args
define sort(list) is shared **Sort the list**
test list := [4, 2, 7, 3] .sort(list) assert list = [2, 3, 4, 7]
body count := list.count last := count - 1
for i in last
minCandidate := i j := i + 1
while j < count if list[j] < list[minCandidate], minCandidate := j j :+ 1
temp := list[i] list[i] := list[minCandidate] list[minCandidate] := temp </lang>
Racket
<lang racket>
- lang racket
(define (selection-sort xs)
(cond [(empty? xs) '()]
[else (define x0 (apply min xs))
(cons x0 (selection-sort (remove x0 xs)))]))
</lang>
Raku
(formerly Perl 6) Solution 1: <lang perl6>sub selection_sort ( @a is copy ) {
for 0 ..^ @a.end -> $i {
my $min = [ $i+1 .. @a.end ].min: { @a[$_] };
@a[$i, $min] = @a[$min, $i] if @a[$i] > @a[$min];
}
return @a;
}
my @data = 22, 7, 2, -5, 8, 4; say 'input = ' ~ @data; say 'output = ' ~ @data.&selection_sort; </lang>
- Output:
input = 22 7 2 -5 8 4 output = -5 2 4 7 8 22
Solution 2: <lang perl6>sub selectionSort(@tmp) {
for ^@tmp -> $i {
my $min = $i; @tmp[$i, $_] = @tmp[$_, $i] if @tmp[$min] > @tmp[$_] for $i^..^@tmp;
}
return @tmp;
} </lang>
- Output:
input = 22 7 2 -5 8 4 output = -5 2 4 7 8 22
REXX
<lang rexx>/*REXX program sorts a stemmed array using the selection─sort algorithm. */ call init /*assign some values to an array: @. */ call show 'before sort' /*show the before array elements. */
say copies('▒', 65) /*show a nice separator line (fence). */
call selectionSort # /*invoke selection sort (and # items). */ call show ' after sort' /*show the after array elements. */ exit /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ init: @.=; @.1 = '---The seven hills of Rome:---'
@.2 = '=============================='; @.6 = 'Virminal'
@.3 = 'Caelian' ; @.7 = 'Esquiline'
@.4 = 'Palatine' ; @.8 = 'Quirinal'
@.5 = 'Capitoline' ; @.9 = 'Aventine'
do #=1 until @.#==; end /*find the number of items in the array*/
#= #-1; return /*adjust # (because of DO index). */
/*──────────────────────────────────────────────────────────────────────────────────────*/ selectionSort: procedure expose @.; parse arg n
do j=1 for n-1; _= @.j; p= j
do k=j+1 to n; if @.k>=_ then iterate
_= @.k; p= k /*this item is out─of─order, swap later*/
end /*k*/
if p==j then iterate /*if the same, the order of items is OK*/
_= @.j; @.j= @.p; @.p= _ /*swap 2 items that're out─of─sequence.*/
end /*j*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/ show: do i=1 for #; say ' element' right(i,length(#)) arg(1)":" @.i; end; return</lang>
- output:
element 1 before sort: ---The seven hills of Rome:---
element 2 before sort: ==============================
element 3 before sort: Caelian
element 4 before sort: Palatine
element 5 before sort: Capitoline
element 6 before sort: Virminal
element 7 before sort: Esquiline
element 8 before sort: Quirinal
element 9 before sort: Aventine
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
element 1 after sort: ---The seven hills of Rome:---
element 2 after sort: ==============================
element 3 after sort: Aventine
element 4 after sort: Caelian
element 5 after sort: Capitoline
element 6 after sort: Esquiline
element 7 after sort: Palatine
element 8 after sort: Quirinal
element 9 after sort: Virminal
Ring
<lang ring> aList = [7,6,5,9,8,4,3,1,2,0] see sortList(aList)
func sortList list
count = len(list) + 1
last = count - 1
for i = 1 to last
minCandidate = i
j = i + 1
while j < count
if list[j] < list[minCandidate] minCandidate = j ok j = j + 1
end
temp = list[i]
list[i] = list[minCandidate]
list[minCandidate] = temp
next
return list
</lang>
Ruby
<lang ruby>
- a relatively readable version - creates a distinct array
def sequential_sort(array)
sorted = []
while array.any? index_of_smallest_element = find_smallest_index(array) # defined below sorted << array.delete_at(index_of_smallest_element) end
sorted
end
def find_smallest_index(array)
smallest_element = array[0] smallest_index = 0
array.each_with_index do |ele, idx|
if ele < smallest_element
smallest_element = ele
smallest_index = idx
end
end
smallest_index
end
puts "sequential_sort([9, 6, 8, 7, 5]): #{sequential_sort([9, 6, 8, 7, 5])}"
- prints: sequential_sort([9, 6, 8, 7, 5]): [5, 6, 7, 8, 9]
- more efficient version - swaps the array's elements in place
def sequential_sort_with_swapping(array)
array.each_with_index do |element, index| smallest_unsorted_element_so_far = element smallest_unsorted_index_so_far = index
(index+1...array.length).each do |index_value|
if array[index_value] < smallest_unsorted_element_so_far
smallest_unsorted_element_so_far = array[index_value]
smallest_unsorted_index_so_far = index_value
end
end
# swap index_value-th smallest element for index_value-th element array[index], array[smallest_unsorted_index_so_far] = array[smallest_unsorted_index_so_far], array[index] end
array
end
puts "sequential_sort_with_swapping([7,6,5,9,8,4,3,1,2,0]): #{sequential_sort_with_swapping([7,6,5,9,8,4,3,1,2,0])}"
- prints: sequential_sort_with_swapping([7,6,5,9,8,4,3,1,2,0]): [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
</lang>
Run BASIC
<lang runbasic>siz = 10 dim srdData(siz) for i = 1 to siz srtData(i) = rnd(0) * 100 next i
FOR i = 1 TO siz-1
lo = i
FOR j = (i + 1) TO siz
IF srtData(j) < srtData(lo) lo = j
NEXT j
if i <> lo then
temp = srtData(i)
srtData(i) = srtData(lo)
srtData(lo) = temp
end if
NEXT i
for i = 1 to siz print i;chr$(9);srtData(i) next i</lang>
1 20.5576419 2 32.4299311 3 48.345375 4 54.135847 5 63.1427764 6 67.8079128 7 85.2134895 8 91.3576602 9 95.4280853 10 98.8323211
Rust
<lang rust> fn selection_sort(array: &mut [i32]) {
let mut min;
for i in 0..array.len() {
min = i;
for j in (i+1)..array.len() {
if array[j] < array[min] {
min = j;
}
}
let tmp = array[i];
array[i] = array[min];
array[min] = tmp;
}
}
fn main() {
let mut array = [ 9, 4, 8, 3, -5, 2, 1, 6 ];
println!("The initial array is {:?}", array);
selection_sort(&mut array);
println!(" The sorted array is {:?}", array);
} </lang>
Scala
<lang scala>def swap(a: Array[Int], i1: Int, i2: Int) = { val tmp = a(i1); a(i1) = a(i2); a(i2) = tmp }
def selectionSort(a: Array[Int]) =
for (i <- 0 until a.size - 1)
swap(a, i, (i + 1 until a.size).foldLeft(i)((currMin, index) =>
if (a(index) < a(currMin)) index else currMin))</lang>
This version avoids the extra definition by using a function literal:
<lang scala>def selectionSort(a: Array[Int]) = for (i <- 0 until a.size - 1) (
{ (i1: Int, i2: Int) => val tmp = a(i1); a(i1) = a(i2); a(i2) = tmp }
) (i, (i + 1 until a.size).foldLeft(i)((currMin, index) => if (a(index) < a(currMin)) index else currMin) )</lang>
Functional way: <lang scala>def selectionSort[T <% Ordered[T]](list: List[T]): List[T] = {
def remove(e: T, list: List[T]): List[T] =
list match {
case Nil => Nil
case x :: xs if x == e => xs
case x :: xs => x :: remove(e, xs)
}
list match {
case Nil => Nil
case _ =>
val min = list.min
min :: selectionSort(remove(min, list))
}
} </lang>
Seed7
<lang seed7>const proc: selectionSort (inout array elemType: arr) is func
local
var integer: i is 0;
var integer: j is 0;
var integer: min is 0;
var elemType: help is elemType.value;
begin
for i range 1 to length(arr) - 1 do
min := i;
for j range i + 1 to length(arr) do
if arr[j] < arr[min] then
min := j;
end if;
end for;
help := arr[min];
arr[min] := arr[i];
arr[i] := help;
end for;
end func;</lang>
Original source: [1]
Sidef
<lang ruby>class Array {
method selectionsort {
for i in ^(self.end) {
var min_idx = i
for j in (i+1 .. self.end) {
if (self[j] < self[min_idx]) {
min_idx = j
}
}
self.swap(i, min_idx)
}
return self
}
}
var nums = [7,6,5,9,8,4,3,1,2,0]; say nums.selectionsort;
var strs = ["John", "Kate", "Zerg", "Alice", "Joe", "Jane"]; say strs.selectionsort;</lang>
Standard ML
<lang sml>fun selection_sort [] = []
| selection_sort (first::lst) =
let
val (small, output) = foldl
(fn (x, (small, output)) =>
if x < small then
(x, small::output)
else
(small, x::output)
) (first, []) lst
in
small :: selection_sort output
end</lang>
Stata
<lang stata>mata function selection_sort(real vector a) { real scalar i, j, k, n n = length(a) for (i = 1; i < n; i++) { k = i for (j = i+1; j <= n; j++) { if (a[j] < a[k]) k = j } if (k != i) a[(i, k)] = a[(k, i)] } } end</lang>
Swift
<lang Swift>func selectionSort(inout arr:[Int]) {
var min:Int
for n in 0..<arr.count {
min = n
for x in n+1..<arr.count {
if (arr[x] < arr[min]) {
min = x
}
}
if min != n {
let temp = arr[min]
arr[min] = arr[n]
arr[n] = temp
}
}
}</lang>
Tcl
<lang tcl>package require Tcl 8.5 package require struct::list
proc selectionsort {A} {
set len [llength $A]
for {set i 0} {$i < $len - 1} {incr i} {
set min_idx [expr {$i + 1}]
for {set j $min_idx} {$j < $len} {incr j} {
if {[lindex $A $j] < [lindex $A $min_idx]} {
set min_idx $j
}
}
if {[lindex $A $i] > [lindex $A $min_idx]} {
struct::list swap A $i $min_idx
}
}
return $A
}
puts [selectionsort {8 6 4 2 1 3 5 7 9}] ;# => 1 2 3 4 5 6 7 8 9</lang>
TI-83 BASIC
Store input into L1 and prgmSORTSLCT will store the sorted output into L2.
:L1→L2 :dim(L2)→I :For(A,1,I) :A→C :0→X :For(B,A,I) :If L2(B)<L2(C) :Then :B→C :1→X :End :End :If X=1 :Then :L2(C)→B :L2(A)→L2(C) :B→L2(A) :End :End :DelVar A :DelVar B :DelVar C :DelVar I :DelVar X :Return
uBasic/4tH
<lang>PRINT "Selection sort:"
n = FUNC (_InitArray) PROC _ShowArray (n) PROC _Selectionsort (n) PROC _ShowArray (n)
END
_Selectionsort PARAM (1) ' Selection sort
LOCAL (3)
FOR b@ = 0 TO a@-1 c@ = b@
FOR d@ = b@ TO a@-1
IF @(d@) < @(c@) THEN c@ = d@
NEXT
IF b@ # c@ THEN PROC _Swap (b@, c@) NEXT
RETURN
_Swap PARAM(2) ' Swap two array elements
PUSH @(a@) @(a@) = @(b@) @(b@) = POP()
RETURN
_InitArray ' Init example array
PUSH 4, 65, 2, -31, 0, 99, 2, 83, 782, 1 FOR i = 0 TO 9 @(i) = POP() NEXT
RETURN (i)
_ShowArray PARAM (1) ' Show array subroutine
FOR i = 0 TO a@-1 PRINT @(i), NEXT PRINT
RETURN</lang>
Ursala
The selection_sort function is parameterized by a relational predicate p. There are no arrays in Ursala so it uses a list, and the selected item is deleted from the list and inserted into another on each iteration rather than swapped with a preceding item of the same list. <lang Ursala>#import std
selection_sort "p" = @iNX ~&l->rx ^(gldif ==,~&r)^/~&l ^|C/"p"$- ~&</lang> This is already a bad way to code a sorting algorithm in this language, but with only a bit more work, we can get a bigger and slower version that more closely simulates the operations of repeatedly reordering an array. <lang Ursala>selection_sort "p" = ~&itB^?a\~&a ^|JahPfatPRC/~& ~=-~BrhPltPClhPrtPCTlrTQrS^D/"p"$- ~&</lang> Here is a test program sorting by the partial order relation on natural numbers. <lang Ursala>#import nat
- cast %nL
example = selection_sort(nleq) <294,263,240,473,596,392,621,348,220,815></lang>
- Output:
<220,240,263,294,348,392,473,596,621,815>
VBA
I shameless stole the swap function from the bubblesort VBscript implementation.
<lang VBA> sub swap( byref a, byref b) dim tmp tmp = a a = b b = tmp end sub
function selectionSort (a) for i = 0 to ubound(a) k = i for j=i+1 to ubound(a) if a(j) < a(i) then swap a(i), a(j) end if next next selectionSort = a end function </lang>
VBScript
<lang vb>Function Selection_Sort(s) arr = Split(s,",") For i = 0 To UBound(arr) For j = i To UBound(arr) temp = arr(i) If arr(j) < arr(i) Then arr(i) = arr(j) arr(j) = temp End If Next Next Selection_Sort = (Join(arr,",")) End Function
WScript.StdOut.Write "Pre-Sort" & vbTab & "Sorted" WScript.StdOut.WriteLine WScript.StdOut.Write "3,2,5,4,1" & vbTab & Selection_Sort("3,2,5,4,1") WScript.StdOut.WriteLine WScript.StdOut.Write "c,e,b,a,d" & vbTab & Selection_Sort("c,e,b,a,d")</lang>
- Output:
Pre-Sort Sorted 3,2,5,4,1 1,2,3,4,5 c,e,b,a,d a,b,c,d,e
Wren
<lang ecmascript>var selectionSort = Fn.new { |a|
var last = a.count - 1
for (i in 0...last) {
var aMin = a[i]
var iMin = i
for (j in i+1..last) {
if (a[j] < aMin) {
aMin = a[j]
iMin = j
}
}
var t = a[i]
a[i] = aMin
a[iMin] = t
}
}
var as = [ [4, 65, 2, -31, 0, 99, 2, 83, 782, 1], [7, 5, 2, 6, 1, 4, 2, 6, 3] ] for (a in as) {
System.print("Before: %(a)")
selectionSort.call(a)
System.print("After : %(a)")
System.print()
}</lang>
- Output:
Before: [4, 65, 2, -31, 0, 99, 2, 83, 782, 1] After : [-31, 0, 1, 2, 2, 4, 65, 83, 99, 782] Before: [7, 5, 2, 6, 1, 4, 2, 6, 3] After : [1, 2, 2, 3, 4, 5, 6, 6, 7]
Alternatively we can just call a library method.
<lang ecmascript>import "/sort" for Sort
var as = [ [4, 65, 2, -31, 0, 99, 2, 83, 782, 1], [7, 5, 2, 6, 1, 4, 2, 6, 3] ] for (a in as) {
System.print("Before: %(a)")
Sort.selection(a)
System.print("After : %(a)")
System.print()
}</lang>
- Output:
As above.
XPL0
<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations string 0; \use zero-terminated strings
proc SelSort(A, N); \Selection sort char A; \address of array int N; \number of elements in array (size) int I, J, S, JS, T; [for I:= 0 to N-2 do
[S:= (~0)>>1;
for J:= I to N-1 do \find smallest element
if A(J) < S then [S:= A(J); JS:= J];
T:= A(I); A(I):= A(JS); A(JS):= T;
];
];
func StrLen(Str); \Return number of characters in an ASCIIZ string char Str; int I; for I:= 0 to -1>>1-1 do
if Str(I) = 0 then return I;
char Str; [Str:= "Pack my box with five dozen liquor jugs."; SelSort(Str, StrLen(Str)); Text(0, Str); CrLf(0); ]</lang>
- Output:
.Pabcdeefghiiijklmnoooqrstuuvwxyz
zkl
<lang zkl>fcn selectionSort(list){ // sort a list of ints
copy,r:=list.copy(),List();
while(copy){
min,idx:=(0).min(copy), copy.find(min);
r.append(min);
copy.del(idx);
}
r
}</lang> <lang zkl>selectionSort(List(28, 44, 46, 24, 19, -5, 2, 17, 11, 25, 4)).println();</lang>
- Output:
L(-5,2,4,11,17,19,24,25,28,44,46)
- Programming Tasks
- Sorting Algorithms
- Sorting
- 11l
- 360 Assembly
- AArch64 Assembly
- ActionScript
- Ada
- ALGOL 68
- ARM Assembly
- Arturo
- AutoHotkey
- AWK
- BBC BASIC
- BASIC
- GWBASIC
- C
- C sharp
- C++
- Clojure
- COBOL
- Common Lisp
- Crystal
- D
- Delphi
- E
- EasyLang
- EchoLisp
- Eiffel
- Elena
- Elixir
- Erlang
- Euphoria
- F Sharp
- Factor
- Forth
- Fortran
- FreeBASIC
- Gambas
- GAP
- Go
- Haskell
- Haxe
- Icon
- Unicon
- Io
- IS-BASIC
- J
- Java
- JavaScript
- Jq
- Julia
- Kotlin
- Liberty BASIC
- LSE
- Lua
- Maple
- Mathematica
- MATLAB
- Octave
- Maxima
- MAXScript
- N/t/roff
- Nanoquery
- Nemerle
- NetRexx
- Nim
- OCaml
- Oforth
- OoRexx
- Oz
- PARI/GP
- Pascal
- Perl
- Phix
- PHP
- PicoLisp
- PL/I
- PowerShell
- Prolog
- PureBasic
- Python
- Qi
- Quackery
- R
- Ra
- Racket
- Raku
- REXX
- Ring
- Ruby
- Run BASIC
- Rust
- Scala
- Seed7
- Sidef
- Standard ML
- Stata
- Swift
- Tcl
- Tcllib
- TI-83 BASIC
- UBasic/4tH
- Ursala
- VBA
- VBScript
- Wren
- Wren-sort
- XPL0
- Zkl
- GUISS/Omit