Sorting algorithms/Strand sort: Difference between revisions
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{{task|Sorting Algorithms}}
{{Sorting Algorithm}}
[[Category:Sorting]]
{{Wikipedia|Strand sort}}
<br>
;Task:
Implement the [[wp:Strand sort|Strand sort]].
This is a way of sorting numbers by extracting shorter sequences of already sorted numbers from an unsorted list.
<br><br>
=={{header|11l}}==
{{trans|Python}}
<syntaxhighlight lang="11l">F merge_list(&a, &b)
[Int] out
L !a.empty & !b.empty
I a[0] < b[0]
out.append(a.pop(0))
E
out.append(b.pop(0))
out [+]= a
out [+]= b
R out
F strand(&a)
V i = 0
V s = [a.pop(0)]
L i < a.len
I a[i] > s.last
s.append(a.pop(i))
E
i++
R s
F strand_sort(&a)
V out = strand(&a)
L !a.empty
out = merge_list(&out, &strand(&a))
R out
print(strand_sort(&[1, 6, 3, 2, 1, 7, 5, 3]))</syntaxhighlight>
{{out}}
<pre>
[1, 1, 2, 3, 3, 5, 6, 7]
</pre>
=={{header|AppleScript}}==
Strand sort seems to be essentially a merge sort with a particular way of setting up the initial blocks.
<syntaxhighlight lang="applescript">-- Sort items l thru r of theList in place, ascending.
on strandSort(theList, l, r)
-- Deal with negative and/or transposed range index parameters.
set listLength to (count theList)
if (l < 0) then set l to listLength + l + 1
if (r < 0) then set r to listLength + r + 1
if (l > r) then set {l, r} to {r, l}
if ((l < 1) or (r > listLength)) then error "strandSort(): range index parameter(s) outside list range."
script o
property dest : theList -- Original list.
property src : my dest's items l thru r -- The items in the sort range.
property ranges : {}
end script
-- Individually list-wrap the items in o's src to avoid having to
-- hard-code their actual class in the line marked ** below.
repeat with i from 1 to (r - l + 1)
set o's src's item i to {o's src's item i}
end repeat
-- Extract "strands" of existing order from the sort range items
-- and write the resulting runs over the range in the original list.
set i to l
repeat until (i > r)
set j to i
set jv to o's src's beginning's beginning -- The value in src's first sublist.
set o's dest's item j to jv -- Store it in the next original-list slot
set o's src's item 1 to missing value -- Replace the sublist with a placeholder.
-- Do the same with any later values that are sequentially greater or equal.
repeat with k from 2 to (count o's src)
set kv to o's src's item k's beginning
if (kv < jv) then
else
set j to j + 1
set o's dest's item j to kv
set jv to kv
set o's src's item k to missing value
end if
end repeat
set o's ranges's end to {i, j} -- Note this strand's range in the list.
set o's src to o's src's lists -- Lose src's zapped sublists. **
set i to j + 1
end repeat
set strandCount to (count o's ranges)
if (strandCount = 1) then return -- The input list was already in order.
-- Work out how many passes the iterative merge will take and from this whether
-- the auxiliary list has to be the source or the destination during the first pass.
-- The destination in the final pass has to be the original list.
set passCount to 0
repeat while (2 ^ passCount < strandCount)
set passCount to passCount + 1
end repeat
if (passCount mod 2 = 0) then
set o's src to o's dest
set o's dest to o's dest's items
else
set o's src to o's dest's items
end if
-- Merge the strands.
repeat passCount times
set k to l -- Destination index.
repeat with rr from 2 to strandCount by 2 -- Per pair of ranges.
set {{i, ix}, {j, jx}} to o's ranges's items (rr - 1) thru rr
set o's ranges's item (rr - 1) to {i, jx}
set o's ranges's item rr to missing value
set iv to o's src's item i
set jv to o's src's item j
repeat until (k > jx)
if (iv > jv) then
set o's dest's item k to jv
if (j < jx) then
set j to j + 1
set jv to o's src's item j
else
repeat with i from i to ix
set k to k + 1
set o's dest's item k to o's src's item i
end repeat
end if
else
set o's dest's item k to iv
if (i < ix) then
set i to i + 1
set iv to o's src's item i
else
repeat with k from j to jx
set o's dest's item k to o's src's item k
end repeat
end if
end if
set k to k + 1
end repeat
end repeat
if (rr < strandCount) then -- Odd range at the end of this pass?
set {i, ix} to o's ranges's end
repeat with k from i to ix
set o's dest's item k to o's src's item k
end repeat
end if
set o's ranges to o's ranges's lists
set strandCount to (strandCount + 1) div 2
set {o's src, o's dest} to {o's dest, o's src}
end repeat
return -- nothing.
end strandSort
local lst
set lst to {5, 1, 4, 37, 2, 0, 9, 6, -44, 3, 8, 7}
strandSort(lst, 1, -1)
return lst</syntaxhighlight>
{{output}}
<syntaxhighlight lang="applescript">{-44, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 37}</syntaxhighlight>
=={{header|AutoHotkey}}==
{{works with|AutoHotkey_L}}
<syntaxhighlight lang="autohotkey">string =
(
-2 0 -2 5 5 3 -1 -3 5 5 0 2 -4 4 2
)
string2 := string
Loop
{
loop, parse, string, %A_space%
{
list := 1 = A_index ? A_loopfield : list
StringSplit, k, list, %A_space%
if ( k%k0% <= A_loopfield ) && ( l != "" ) && ( A_index != 1 )
list := list . " " . A_loopfield
if ( k%k0% > A_loopfield )
list := A_loopfield . " " . list , index++
l := A_loopfield
}
if ( index = 0 )
{
MsgBox % "unsorted:" string2 "`n Sorted:" list
exitapp
}
string := list, list = "", index := 0
}
esc::ExitApp</syntaxhighlight>outout<syntaxhighlight lang="text">
unsorted:-2 0 -2 5 5 3 -1 -3 5 5 0 2 -4 4 2
Sorted:-4 -3 -2 -2 -1 0 0 2 2 3 4 5 5 5 5</syntaxhighlight>
=={{header|C}}==
Strand sort using singly linked list. C99, compiled with <code>gcc -std=c99</code>
<syntaxhighlight lang="c">#include <stdio.h>
typedef struct node_t *node, node_t;
struct node_t { int v; node next; };
typedef struct { node head, tail; } slist;
void push(slist *l, node e) {
if (!l->head) l->head = e;
if (l->tail) l->tail->next = e;
l->tail = e;
}
node removehead(slist *l) {
node e = l->head;
if (e) {
l->head = e->next;
e->next = 0;
}
return e;
}
void join(slist *a, slist *b) {
push(a, b->head);
a->tail = b->tail;
}
void merge(slist *a, slist *b) {
slist r = {0};
while (a->head && b->head)
push(&r, removehead(a->head->v <= b->head->v ? a : b));
join(&r, a->head ? a : b);
*a = r;
b->head = b->tail = 0;
}
void sort(int *ar, int len)
{
node_t all[len];
// array to list
for (int i = 0; i < len; i++)
all[i].v = ar[i], all[i].next = i < len - 1 ? all + i + 1 : 0;
slist list = {all, all + len - 1}, rem, strand = {0}, res = {0};
for (node e = 0; list.head; list = rem) {
rem.head = rem.tail = 0;
while ((e = removehead(&list)))
push((!strand.head || e->v >= strand.tail->v) ? &strand : &rem, e);
merge(&res, &strand);
}
// list to array
for (int i = 0; res.head; i++, res.head = res.head->next)
ar[i] = res.head->v;
}
void show(const char *title, int *x, int len)
{
printf("%s ", title);
for (int i = 0; i < len; i++)
printf("%3d ", x[i]);
putchar('\n');
}
int main(void)
{
int x[] = {-2,0,-2,5,5,3,-1,-3,5,5,0,2,-4,4,2};
# define SIZE sizeof(x)/sizeof(int)
show("before sort:", x, SIZE);
sort(x, sizeof(x)/sizeof(int));
show("after sort: ", x, SIZE);
return 0;
}</syntaxhighlight>outout<syntaxhighlight lang="text">before sort: -2 0 -2 5 5 3 -1 -3 5 5 0 2 -4 4 2
after sort: -4 -3 -2 -2 -1 0 0 2 2 3 4 5 5 5 5</syntaxhighlight>
=={{header|C++}}==
<syntaxhighlight lang="cpp">#include <list>
template <typename T>
std::list<T> strandSort(std::list<T> lst) {
if (lst.size() <= 1)
return lst;
std::list<T> result;
std::list<T> sorted;
while (!lst.empty()) {
sorted.push_back(lst.front());
lst.pop_front();
for (typename std::list<T>::iterator it = lst.begin(); it != lst.end(); ) {
if (sorted.back() <= *it) {
sorted.push_back(*it);
it = lst.erase(it);
} else
it++;
}
result.merge(sorted);
}
return result;
}</syntaxhighlight>
=={{header|Clojure}}==
<syntaxhighlight lang="clojure">(ns rosettacode.strand-sort)
(defn merge-join
"Produces a globally sorted seq from two sorted seqables"
[[a & la :as all] [b & lb :as bll]]
(cond (nil? a) bll
(nil? b) all
(< a b) (cons a (lazy-seq (merge-join la bll)))
true (cons b (lazy-seq (merge-join all lb)))))
(defn unbraid
"Separates a sorted list from a sequence"
[u]
(when (seq u)
(loop [[x & xs] u
u []
s []
e x]
(if (nil? x)
[s u]
(if (>= x e)
(recur xs u (conj s x) x)
(recur xs (conj u x) s e))))))
(defn strand-sort
"http://en.wikipedia.org/wiki/Strand_sort"
[s]
(loop [[s u] (unbraid s)
m nil]
(if s
(recur (unbraid u) (merge-join m s))
m)))
(strand-sort [1, 6, 3, 2, 1, 7, 5, 3])
;;=> (1 1 2 3 3 5 6 7)
</syntaxhighlight>
=={{header|CMake}}==
Only for lists of integers.
<syntaxhighlight lang="cmake"># strand_sort(<output variable> [<value>...]) sorts a list of integers.
function(strand_sort var)
# Strand sort moves elements from _ARGN_ to _answer_.
set(answer) # answer: a sorted list
while(DEFINED ARGN)
# Split _ARGN_ into two lists, _accept_ and _reject_.
set(accept) # accept: elements in sorted order
set(reject) # reject: all other elements
set(p)
foreach(e ${ARGN})
if(DEFINED p AND p GREATER ${e})
list(APPEND reject ${e})
else()
list(APPEND accept ${e})
set(p ${e})
endif()
endforeach(e)
# Prepare to merge _accept_ into _answer_. First, convert both lists
# into arrays, for better indexing: set(e ${answer${i}}) is faster
# than list(GET answer ${i} e).
set(la 0)
foreach(e ${answer})
math(EXPR la "${la} + 1")
set(answer${la} ${e})
endforeach(e)
set(lb 0)
foreach(e ${accept})
math(EXPR lb "${lb} + 1")
set(accept${lb} ${e})
endforeach(e)
# Merge _accept_ into _answer_.
set(answer)
set(ia 1)
set(ib 1)
while(NOT ia GREATER ${la}) # Iterate elements of _answer_.
set(ea ${answer${ia}})
while(NOT ib GREATER ${lb}) # Take elements from _accept_,
set(eb ${accept${ib}}) # while they are less than
if(eb LESS ${ea}) # next element of _answer_.
list(APPEND answer ${eb})
math(EXPR ib "${ib} + 1")
else()
break()
endif()
endwhile()
list(APPEND answer ${ea}) # Take next from _answer_.
math(EXPR ia "${ia} + 1")
endwhile()
while(NOT ib GREATER ${lb}) # Take rest of _accept_.
list(APPEND answer ${accept${ib}})
math(EXPR ib "${ib} + 1")
endwhile()
# This _reject_ becomes next _ARGN_. If _reject_ is empty, then
# set(ARGN) undefines _ARGN_, breaking the loop.
set(ARGN ${reject})
endwhile(DEFINED ARGN)
set("${var}" ${answer} PARENT_SCOPE)
endfunction(strand_sort)</syntaxhighlight>
<syntaxhighlight lang="cmake">strand_sort(result 11 55 55 44 11 33 33 44 22 22)
message(STATUS "${result}") # -- 11;11;22;22;33;33;44;44;55;55</syntaxhighlight>
=={{header|Common Lisp}}==
<syntaxhighlight lang="lisp">(defun strand-sort (l cmp)
(if l
(let* ((l (reverse l))
(o (list (car l))) n)
(loop for i in (cdr l) do
(push i (if (funcall cmp (car o) i) n o)))
(merge 'list o (strand-sort n cmp) #'<))))
(let ((r (loop repeat 15 collect (random 10))))
(print r)
(print (strand-sort r #'<)))</syntaxhighlight>output<syntaxhighlight lang="text">(5 8 6 0 6 8 4 7 0 7 1 5 3 3 6)
(0 0 1 3 3 4 5 5 6 6 6 7 7 8 8)</syntaxhighlight>
=={{header|D}}==
=== Using doubly linked lists ===
<syntaxhighlight lang="d">import std.stdio, std.container;
DList!T strandSort(T)(DList!T list) {
static DList!T merge(DList!T left, DList!T right) {
DList!T result;
while (!left.empty && !right.empty) {
if (left.front <= right.front) {
result.insertBack(left.front);
left.removeFront();
} else {
result.insertBack(right.front);
right.removeFront();
}
}
result.insertBack(left[]);
result.insertBack(right[]);
return result;
}
DList!T result, sorted, leftover;
while (!list.empty) {
leftover.clear();
sorted.clear();
sorted.insertBack(list.front);
list.removeFront();
foreach (item; list) {
if (sorted.back <= item)
sorted.insertBack(item);
else
leftover.insertBack(item);
}
result = merge(sorted, result);
list = leftover;
}
return result;
}
void main() {
auto lst = DList!int([-2,0,-2,5,5,3,-1,-3,5,5,0,2,-4,4,2]);
foreach (e; strandSort(lst))
write(e, " ");
}</syntaxhighlight>
{{out}}
<pre>-4 -3 -2 -2 -1 0 0 2 2 3 4 5 5 5 5 </pre>
=== Faster version using slices ===
<syntaxhighlight lang="d">import std.stdio, std.array;
T[] strandSort(T)(const(T)[] list) pure nothrow {
static T[] merge(const(T)[] left, const(T)[] right) pure nothrow {
T[] res;
while (!left.empty && !right.empty) {
if (left.front <= right.front) {
res ~= left.front;
left.popFront;
} else {
res ~= right.front;
right.popFront;
}
}
return res ~ left ~ right;
}
T[] result;
while (!list.empty) {
auto sorted = list[0 .. 1];
list.popFront;
typeof(sorted) leftover;
foreach (const item; list)
(sorted.back <= item ? sorted : leftover) ~= item;
result = merge(sorted, result);
list = leftover;
}
return result;
}
void main() {
const arr = [-2, 0, -2, 5, 5, 3, -1, -3, 5, 5, 0, 2, -4, 4, 2];
arr.strandSort.writeln;
}</syntaxhighlight>
{{out}}
<pre>[-4, -3, -2, -2, -1, 0, 0, 2, 2, 3, 4, 5, 5, 5, 5]</pre>
=={{header|EasyLang}}==
{{trans|11l}}
<syntaxhighlight>
proc merge . a[] b[] .
a = 1 ; b = 1
while a <= len a[] and b <= len b[]
if a[a] < b[b]
r[] &= a[a]
a += 1
else
r[] &= b[b]
b += 1
.
.
while a <= len a[]
r[] &= a[a]
a += 1
.
while b <= len b[]
r[] &= b[b]
b += 1
.
swap a[] r[]
.
proc strand . a[] s[] .
s[] = [ a[1] ]
for i = 2 to len a[]
if a[i] > s[$]
s[] &= a[i]
else
an[] &= a[i]
.
.
swap a[] an[]
.
proc strandsort . a[] .
strand a[] out[]
while len a[] > 0
strand a[] b[]
merge out[] b[]
.
swap a[] out[]
.
a[] = [ 1 6 3 2 1 7 5 3 ]
strandsort a[]
print a[]
</syntaxhighlight>
{{out}}
<pre>
[ 1 1 2 3 3 5 6 7 ]
</pre>
=={{header|Elixir}}==
{{trans|Ruby}}
<syntaxhighlight lang="elixir">defmodule Sort do
def strand_sort(args), do: strand_sort(args, [])
defp strand_sort([], result), do: result
defp strand_sort(a, result) do
{_, sublist, b} = Enum.reduce(a, {hd(a),[],[]}, fn val,{v,l1,l2} ->
if v <= val, do: {val, [val | l1], l2},
else: {v, l1, [val | l2]}
end)
strand_sort(b, :lists.merge(Enum.reverse(sublist), result))
end
end
IO.inspect Sort.strand_sort [7, 17, 6, 20, 20, 12, 1, 1, 9]</syntaxhighlight>
{{out}}
<pre>
[1, 1, 6, 7, 9, 12, 17, 20, 20]
</pre>
=={{header|Euphoria}}==
<syntaxhighlight lang="euphoria">function merge(sequence left, sequence right)
sequence result
result = {}
while length(left) > 0 and length(right) > 0 do
if left[$] <= right[1] then
exit
elsif right[$] <= left[1] then
return result & right & left
elsif left[1] < right[1] then
result = append(result,left[1])
left = left[2..$]
else
result = append(result,right[1])
right = right[2..$]
end if
end while
return result & left & right
end function
function strand_sort(sequence s)
integer j
sequence result
result = {}
while length(s) > 0 do
j = length(s)
for i = 1 to length(s)-1 do
if s[i] > s[i+1] then
j = i
exit
end if
end for
result = merge(result,s[1..j])
s = s[j+1..$]
end while
return result
end function
constant s = rand(repeat(1000,10))
puts(1,"Before: ")
? s
puts(1,"After: ")
? strand_sort(s)</syntaxhighlight>
Output:
<pre>Before: {551,746,940,903,51,18,346,417,340,502}
After: {18,51,340,346,417,502,551,746,903,940}</pre>
=={{header|F_Sharp|F#}}==
<syntaxhighlight lang="fsharp">
// Strand sort. Nigel Galloway: August 18th., 2023
let fN g=let mutable n=g in fun g->if n>g then false else n<-g; true
let fI n=let fN=fN(List.head n) in List.partition fN n
let rec fG n g=[match n,g with [],g|g,[]->yield! g
|n::gn,i::ng when n<i->yield n; yield! fG gn g
|n,g::ng->yield g; yield! fG n ng]
let rec fL n g=match n with []->g |_->let n,i=fI n in fL i (n::g)
let sort n=fL n []|>List.fold(fun n g->fG n g)[]
printfn "%A" (sort ["one";"two";"three";"four"]);;
printfn "%A" (sort [2;3;1;5;11;7;5])
</syntaxhighlight>
{{out}}
<pre>
["four"; "one"; "three"; "two"]
[1; 2; 3; 5; 5; 7; 11]
</pre>
=={{header|Go}}==
<syntaxhighlight lang="go">package main
import "fmt"
type link struct {
int
next *link
}
func linkInts(s []int) *link {
if len(s) == 0 {
return nil
}
return &link{s[0], linkInts(s[1:])}
}
func (l *link) String() string {
if l == nil {
return "nil"
}
r := fmt.Sprintf("[%d", l.int)
for l = l.next; l != nil; l = l.next {
r = fmt.Sprintf("%s %d", r, l.int)
}
return r + "]"
}
func main() {
a := linkInts([]int{170, 45, 75, -90, -802, 24, 2, 66})
fmt.Println("before:", a)
b := strandSort(a)
fmt.Println("after: ", b)
}
func strandSort(a *link) (result *link) {
for a != nil {
// build sublist
sublist := a
a = a.next
sTail := sublist
for p, pPrev := a, a; p != nil; p = p.next {
if p.int > sTail.int {
// append to sublist
sTail.next = p
sTail = p
// remove from a
if p == a {
a = p.next
} else {
pPrev.next = p.next
}
} else {
pPrev = p
}
}
sTail.next = nil // terminate sublist
if result == nil {
result = sublist
continue
}
// merge
var m, rr *link
if sublist.int < result.int {
m = sublist
sublist = m.next
rr = result
} else {
m = result
rr = m.next
}
result = m
for {
if sublist == nil {
m.next = rr
break
}
if rr == nil {
m.next = sublist
break
}
if sublist.int < rr.int {
m.next = sublist
m = sublist
sublist = m.next
} else {
m.next = rr
m = rr
rr = m.next
}
}
}
return
}</syntaxhighlight>
Output:
<pre>
before: [170 45 75 -90 -802 24 2 66]
after: [-802 -90 2 24 45 66 75 170]
</pre>
=={{header|Haskell}}==
<syntaxhighlight lang="haskell">-- Same merge as in Merge Sort
merge :: (Ord a) => [a] -> [a] -> [a]
merge [] ys = ys
merge xs [] = xs
merge (x : xs) (y : ys)
| x <= y = x : merge xs (y : ys)
| otherwise = y : merge (x : xs) ys
strandSort :: (Ord a) => [a] -> [a]
strandSort [] = []
strandSort (x : xs) = merge strand (strandSort rest) where
(strand, rest) = extractStrand x xs
extractStrand x [] = ([x], [])
extractStrand x (x1 : xs)
| x <= x1 = let (strand, rest) = extractStrand x1 xs in (x : strand, rest)
| otherwise = let (strand, rest) = extractStrand x xs in (strand, x1 : rest)</syntaxhighlight>
=={{header|J}}==
Line 8 ⟶ 780:
Using <code>merge</code> defined at [[Sorting algorithms/Merge sort#J]]:
<
Example use:
<
1 2 3 4 5</
Note: the order in which this J implementation processes the strands differs from the pseudocode currently at the wikipedia page on strand sort and matches the haskell implementation currently at the wikipedia page.
Also note that the individual strands can be seen by using <code>;</code> instead of <code>merge</code>.
<syntaxhighlight lang="j"> ((#~ ; $:^:(0<#)@(#~ -.)) (= >./\)) 3 1 5 4 2
┌───┬───┬─┬┐
│3 5│1 4│2││
└───┴───┴─┴┘
((#~ ; $:^:(0<#)@(#~ -.)) (= >./\)) 3 3 1 2 4 3 5 6
┌─────────┬─────┬┐
│3 3 4 5 6│1 2 3││
└─────────┴─────┴┘</syntaxhighlight>
=={{header|Java}}==
{{works with|Java|1.6+}}
<
import java.util.LinkedList;
public class Strand{
// note: the input list is destroyed
public static <E extends Comparable<? super E>>
LinkedList<E> strandSort(LinkedList<E> list){
Line 38 ⟶ 815:
LinkedList<E> sorted = new LinkedList<E>();
sorted.add(list.removeFirst()); //same as remove() or remove(0)
for(
E elem =
if(sorted.peekLast().compareTo(elem) <= 0){
sorted.addLast(elem); //same as add(elem) or add(0, elem)
}
}
Line 70 ⟶ 847:
System.out.println(strandSort(new LinkedList<Integer>(Arrays.asList(3,3,1,2,4,3,5,6))));
}
}</
Output:
<pre>[1, 2, 3, 4, 5]
[1, 2, 3, 3, 4, 5]
[1, 2, 3, 3, 3, 4, 5, 6]</pre>
=={{header|jq}}==
Most of the implementation is the "merge" function for merging two arrays. Notice that the helper function, strand, is defined here as an inner function.<syntaxhighlight lang="jq"># merge input array with array x by comparing the heads of the arrays
# in turn; # if both arrays are sorted, the result will be sorted:
def merge(x):
length as $length
| (x|length) as $xl
| if $length == 0 then x
elif $xl == 0 then .
else
. as $in
| reduce range(0; $xl + $length) as $z
# state [ix, xix, ans]
( [0, 0, []];
if .[0] < $length and
((.[1] < $xl and $in[.[0]] <= x[.[1]]) or .[1] == $xl)
then [(.[0] + 1), .[1], (.[2] + [$in[.[0]]]) ]
else [.[0], (.[1] + 1), (.[2] + [x[.[1]]]) ]
end
) | .[2]
end ;
def strand_sort:
# The inner function emits [strand, remainder]
def strand:
if length <= 1 then .
else
reduce .[] as $x
# state: [strand, remainder]
([ [], [] ];
if ((.[0]|length) == 0) or .[0][-1] <= $x
then [ (.[0] + [$x]), .[1] ]
else [ .[0], (.[1] + [$x]) ]
end )
end ;
if length <= 1 then .
else strand as $s
| ($s[0] | merge( $s[1] | strand_sort))
end ;
</syntaxhighlight>
Example:
[1,3,5,2,4,6] | strand_sort
=={{header|Julia}}==
{{trans|Python}}
<syntaxhighlight lang="julia">function mergelist(a, b)
out = Vector{Int}()
while !isempty(a) && !isempty(b)
if a[1] < b[1]
push!(out, popfirst!(a))
else
push!(out, popfirst!(b))
end
end
append!(out, a)
append!(out, b)
out
end
function strand(a)
i, s = 1, [popfirst!(a)]
while i < length(a) + 1
if a[i] > s[end]
append!(s, splice!(a, i))
else
i += 1
end
end
s
end
strandsort(a) = (out = strand(a); while !isempty(a) out = mergelist(out, strand(a)) end; out)
println(strandsort([1, 6, 3, 2, 1, 7, 5, 3]))
</syntaxhighlight>{{output}}<pre>
[1, 1, 2, 3, 3, 5, 6, 7]
</pre>
=={{header|Kotlin}}==
{{trans|D}}
<syntaxhighlight lang="scala">// version 1.1.2
fun <T : Comparable<T>> strandSort(l: List<T>): List<T> {
fun merge(left: MutableList<T>, right: MutableList<T>): MutableList<T> {
val res = mutableListOf<T>()
while (!left.isEmpty() && !right.isEmpty()) {
if (left[0] <= right[0]) {
res.add(left[0])
left.removeAt(0)
}
else {
res.add(right[0])
right.removeAt(0)
}
}
res.addAll(left)
res.addAll(right)
return res
}
var list = l.toMutableList()
var result = mutableListOf<T>()
while (!list.isEmpty()) {
val sorted = mutableListOf(list[0])
list.removeAt(0)
val leftover = mutableListOf<T>()
for (item in list) {
if (sorted.last() <= item)
sorted.add(item)
else
leftover.add(item)
}
result = merge(sorted, result)
list = leftover
}
return result
}
fun main(args: Array<String>) {
val l = listOf(-2, 0, -2, 5, 5, 3, -1, -3, 5, 5, 0, 2, -4, 4, 2)
println(strandSort(l))
}</syntaxhighlight>
{{out}}
<pre>
[-4, -3, -2, -2, -1, 0, 0, 2, 2, 3, 4, 5, 5, 5, 5]
</pre>
=={{header|Mathematica}}/{{header|Wolfram Language}}==
<syntaxhighlight lang="mathematica">StrandSort[ input_ ] := Module[ {results = {}, A = input},
While[Length@A > 0,
sublist = {A[[1]]}; A = A[[2;;All]];
For[i = 1, i < Length@A, i++,
If[ A[[i]] > Last@sublist, AppendTo[sublist, A[[i]]]; A = Delete[A, i];]
];
results = #[[Ordering@#]]&@Join[sublist, results];];
results ]
StrandSort[{2, 3, 7, 5, 1, 4, 7}]</syntaxhighlight>
{{out}}
<pre>{1, 2, 3, 4, 5, 7, 7}</pre>
=={{header|MAXScript}}==
<syntaxhighlight lang="maxscript">fn strandSort arr =
(
arr = deepcopy arr
local sub = #()
local results = #()
while arr.count > 0 do
(
sub = #()
append sub (amax arr)
deleteitem arr (for i in 1 to arr.count where arr[i] == amax arr collect i)[1]
local i = 1
while i <= arr.count do
(
if arr[i] > sub[sub.count] do
(
append sub arr[i]
deleteitem arr i
)
i += 1
)
results = join sub results
)
return results
)</syntaxhighlight>
Output:
<syntaxhighlight lang="maxscript">
a = for i in 1 to 20 collect random 1 40
#(19, 26, 14, 31, 11, 33, 2, 14, 32, 28, 12, 38, 2, 37, 27, 18, 31, 24, 39, 28)
strandSort a
#(2, 2, 11, 12, 14, 14, 18, 19, 24, 26, 27, 28, 28, 31, 31, 32, 33, 37, 38, 39)
</syntaxhighlight>
=={{header|NetRexx}}==
<syntaxhighlight 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 -
, strandSort(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 strandSort(A = String[]) public constant binary returns String[]
rl = String[A.length]
al = List strandSort(Arrays.asList(A))
al.toArray(rl)
return rl
method strandSort(Alst = List) public constant binary returns ArrayList
A = ArrayList(Alst)
result = ArrayList()
loop label A_ while A.size > 0
sublist = ArrayList()
sublist.add(A.get(0))
A.remove(0)
loop i_ = 0 while i_ < A.size - 1
if (Comparable A.get(i_)).compareTo(Comparable sublist.get(sublist.size - 1)) > 0 then do
sublist.add(A.get(i_))
A.remove(i_)
end
end i_
result = merge(result, sublist)
end A_
return result
method merge(left = List, right = List) public constant binary returns ArrayList
result = ArrayList()
loop label mx while left.size > 0 & right.size > 0
if (Comparable left.get(0)).compareTo(Comparable right.get(0)) <= 0 then do
result.add(left.get(0))
left.remove(0)
end
else do
result.add(right.get(0))
right.remove(0)
end
end mx
if left.size > 0 then do
result.addAll(left)
end
if right.size > 0 then do
result.addAll(right)
end
return result
</syntaxhighlight>
;Output
<pre>
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
</pre>
=={{header|Nim}}==
<syntaxhighlight lang="nim">proc mergeList[T](a, b: var seq[T]): seq[T] =
result = @[]
while a.len > 0 and b.len > 0:
if a[0] < b[0]:
result.add a[0]
a.delete 0
else:
result.add b[0]
b.delete 0
result.add a
result.add b
proc strand[T](a: var seq[T]): seq[T] =
var i = 0
result = @[a[0]]
a.delete 0
while i < a.len:
if a[i] > result[result.high]:
result.add a[i]
a.delete i
else:
inc i
proc strandSort[T](a: seq[T]): seq[T] =
var a = a
result = a.strand
while a.len > 0:
var s = a.strand
result = mergeList(result, s)
var a = @[1, 6, 3, 2, 1, 7, 5, 3]
echo a.strandSort</syntaxhighlight>
Output:
<pre>@[1, 1, 2, 3, 3, 5, 6, 7]</pre>
=={{header|OCaml}}==
{{trans|Haskell}}
<syntaxhighlight lang="ocaml">let rec strand_sort (cmp : 'a -> 'a -> int) : 'a list -> 'a list = function
[] -> []
| x::xs ->
let rec extract_strand x = function
[] -> [x], []
| x1::xs when cmp x x1 <= 0 ->
let strand, rest = extract_strand x1 xs in x::strand, rest
| x1::xs ->
let strand, rest = extract_strand x xs in strand, x1::rest
in
let strand, rest = extract_strand x xs in
List.merge cmp strand (strand_sort cmp rest)</syntaxhighlight>
usage
<pre>
# strand_sort compare [170; 45; 75; -90; -802; 24; 2; 66];;
- : int list = [-802; -90; 2; 24; 45; 66; 75; 170]
</pre>
=={{header|PARI/GP}}==
<syntaxhighlight lang="parigp">strandSort(v)={
my(sorted=[],unsorted=v,remaining,working);
while(#unsorted,
remaining=working=List();
listput(working, unsorted[1]);
for(i=2,#unsorted,
if(unsorted[i]<working[#working],
listput(remaining, unsorted[i])
,
listput(working, unsorted[i])
)
);
unsorted=Vec(remaining);
sorted=merge(sorted, Vec(working))
);
sorted
};
merge(u,v)={
my(ret=vector(#u+#v),i=1,j=1);
for(k=1,#ret,
if(i<=#u & (j>#v | u[i]<v[j]),
ret[k]=u[i];
i++
,
ret[k]=v[j];
j++
)
);
ret
};</syntaxhighlight>
=={{header|Pascal}}==
<syntaxhighlight lang="pascal">program StrandSortDemo;
type
TIntArray = array of integer;
function merge(left: TIntArray; right: TIntArray): TIntArray;
var
i, j, k: integer;
begin
setlength(merge, length(left) + length(right));
i := low(merge);
j := low(left);
k := low(right);
repeat
if ((left[j] <= right[k]) and (j <= high(left))) or (k > high(right)) then
begin
merge[i] := left[j];
inc(j);
end
else
begin
merge[i] := right[k];
inc(k);
end;
inc(i);
until i > high(merge);
end;
function StrandSort(s: TIntArray): TIntArray;
var
strand: TIntArray;
i, j: integer;
begin
setlength(StrandSort, length(s));
setlength(strand, length(s));
i := low(s);
repeat
StrandSort[i] := s[i];
inc(i);
until (s[i] < s[i-1]);
setlength(StrandSort, i);
repeat
setlength(strand, 1);
j := low(strand);
strand[j] := s[i];
while (s[i+1] > s[i]) and (i < high(s)) do
begin
inc(i);
inc(j);
setlength(strand, length(strand) + 1);
Strand[j] := s[i];
end;
StrandSort := merge(StrandSort, strand);
inc(i);
until (i > high(s));
end;
var
data: TIntArray;
i: integer;
begin
setlength(data, 8);
Randomize;
writeln('The data before sorting:');
for i := low(data) to high(data) do
begin
data[i] := Random(high(data));
write(data[i]:4);
end;
writeln;
data := StrandSort(data);
writeln('The data after sorting:');
for i := low(data) to high(data) do
begin
write(data[i]:4);
end;
writeln;
end.</syntaxhighlight>
=={{header|Perl}}==
<syntaxhighlight lang="perl">use strict;
use warnings;
use feature 'say';
sub merge {
my ($x, $y) = @_;
my @out;
while (@$x and @$y) {
my $t = $x->[-1] <=> $y->[-1];
if ($t == 1) { unshift @out, pop @$x }
elsif ($t == -1) { unshift @out, pop @$y }
else { splice @out, 0, 0, pop(@$x), pop(@$y) }
}
@$x, @$y, @out
}
sub strand {
my $x = shift;
my @out = shift @$x // return;
for (-@$x .. -1) {
push @out, splice @$x, $_, 1 if $x->[$_] >= $out[-1];
}
@out
}
sub strand_sort {
my @x = @_;
my(@out, @strand);
@out = merge \@out, \@strand while @strand = strand(\@x);
@out
}
my @a = map (int rand(100), 1 .. 10);
say "Before @a";
@a = strand_sort(@a);
say "After @a";</syntaxhighlight>
=={{header|Phix}}==
<!--<syntaxhighlight lang="phix">(phixonline)-->
<span style="color: #008080;">with</span> <span style="color: #008080;">javascript_semantics</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">merge</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">left</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">right</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">result</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">left</span><span style="color: #0000FF;">)></span><span style="color: #000000;">0</span>
<span style="color: #008080;">and</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">right</span><span style="color: #0000FF;">)></span><span style="color: #000000;">0</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">left</span><span style="color: #0000FF;">[$]<=</span><span style="color: #000000;">right</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #008080;">exit</span>
<span style="color: #008080;">elsif</span> <span style="color: #000000;">right</span><span style="color: #0000FF;">[$]<=</span><span style="color: #000000;">left</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">result</span> <span style="color: #0000FF;">&</span> <span style="color: #000000;">right</span> <span style="color: #0000FF;">&</span> <span style="color: #000000;">left</span>
<span style="color: #008080;">elsif</span> <span style="color: #000000;">left</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]<</span><span style="color: #000000;">right</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">result</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">result</span><span style="color: #0000FF;">,</span><span style="color: #000000;">left</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">])</span>
<span style="color: #000000;">left</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">left</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$]</span>
<span style="color: #008080;">else</span>
<span style="color: #000000;">result</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">append</span><span style="color: #0000FF;">(</span><span style="color: #000000;">result</span><span style="color: #0000FF;">,</span><span style="color: #000000;">right</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">])</span>
<span style="color: #000000;">right</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">right</span><span style="color: #0000FF;">[</span><span style="color: #000000;">2</span><span style="color: #0000FF;">..$]</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">result</span> <span style="color: #0000FF;">&</span> <span style="color: #000000;">left</span> <span style="color: #0000FF;">&</span> <span style="color: #000000;">right</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #008080;">function</span> <span style="color: #000000;">strand_sort</span><span style="color: #0000FF;">(</span><span style="color: #004080;">sequence</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
<span style="color: #004080;">sequence</span> <span style="color: #000000;">result</span> <span style="color: #0000FF;">=</span> <span style="color: #0000FF;">{}</span>
<span style="color: #008080;">while</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)></span><span style="color: #000000;">0</span> <span style="color: #008080;">do</span>
<span style="color: #004080;">integer</span> <span style="color: #000000;">j</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)</span>
<span style="color: #008080;">for</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">=</span><span style="color: #000000;">1</span> <span style="color: #008080;">to</span> <span style="color: #7060A8;">length</span><span style="color: #0000FF;">(</span><span style="color: #000000;">s</span><span style="color: #0000FF;">)-</span><span style="color: #000000;">1</span> <span style="color: #008080;">do</span>
<span style="color: #008080;">if</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">]></span><span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">i</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">]</span> <span style="color: #008080;">then</span>
<span style="color: #000000;">j</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">i</span>
<span style="color: #008080;">exit</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">for</span>
<span style="color: #000000;">result</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">merge</span><span style="color: #0000FF;">(</span><span style="color: #000000;">result</span><span style="color: #0000FF;">,</span><span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..</span><span style="color: #000000;">j</span><span style="color: #0000FF;">])</span>
<span style="color: #000000;">s</span> <span style="color: #0000FF;">=</span> <span style="color: #000000;">s</span><span style="color: #0000FF;">[</span><span style="color: #000000;">j</span><span style="color: #0000FF;">+</span><span style="color: #000000;">1</span><span style="color: #0000FF;">..$]</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">while</span>
<span style="color: #008080;">return</span> <span style="color: #000000;">result</span>
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">strand_sort</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">shuffle</span><span style="color: #0000FF;">(</span><span style="color: #7060A8;">tagset</span><span style="color: #0000FF;">(</span><span style="color: #000000;">10</span><span style="color: #0000FF;">)))</span>
<!--</syntaxhighlight>-->
{{out}}
<pre>
{1,2,3,4,5,6,7,8,9,10}
</pre>
=={{header|PHP}}==
{{trans|D}}
{{works with|PHP 5.3.0+}}
<syntaxhighlight lang="php">$lst = new SplDoublyLinkedList();
foreach (array(1,20,64,72,48,75,96,55,42,74) as $v)
$lst->push($v);
foreach (strandSort($lst) as $v)
echo "$v ";
function strandSort(SplDoublyLinkedList $lst) {
$result = new SplDoublyLinkedList();
while (!$lst->isEmpty()) {
$sorted = new SplDoublyLinkedList();
$remain = new SplDoublyLinkedList();
$sorted->push($lst->shift());
foreach ($lst as $item) {
if ($sorted->top() <= $item) {
$sorted->push($item);
} else {
$remain->push($item);
}
}
$result = _merge($sorted, $result);
$lst = $remain;
}
return $result;
}
function _merge(SplDoublyLinkedList $left, SplDoublyLinkedList $right) {
$res = new SplDoublyLinkedList();
while (!$left->isEmpty() && !$right->isEmpty()) {
if ($left->bottom() <= $right->bottom()) {
$res->push($left->shift());
} else {
$res->push($right->shift());
}
}
foreach ($left as $v) $res->push($v);
foreach ($right as $v) $res->push($v);
return $res;
}</syntaxhighlight>
<pre>1 20 42 48 55 64 72 74 75 96</pre>
=={{header|PicoLisp}}==
<
(let Res NIL # Result list
(while Lst
Line 97 ⟶ 1,441:
(pop 'Res)
(fifo 'Sub) ) ) ) ) ) ) )
Res ) )</
Test:
<pre>: (strandSort (3 1 5 4 2))
Line 104 ⟶ 1,448:
: (strandSort (3 abc 1 (d e f) 5 T 4 NIL 2))
-> (NIL 1 2 3 4 5 abc (d e f) T)</pre>
=={{header|PL/I}}==
<syntaxhighlight lang="pl/i">strand: procedure options (main); /* 27 Oct. 2012 */
declare A(100) fixed, used(100) bit (1), sorted fixed controlled;
declare (temp, work) fixed controlled;
declare (i, j, k, n) fixed binary;
n = hbound(A, 1);
used = '1'b;
A = random()*99;
put edit (A) (f(3));
do while (allocation(sorted) < n);
call fetch (A, work);
call move (temp, work);
call merge(sorted, temp);
/* Merges elements in SORTED with elements in TEMP. */
end;
/* Transfer the sorted elements to A. */
do i = 1 to allocation(sorted);
A(i) = sorted; free sorted;
end;
/* Print the sorted values. */
put skip list ('The sorted values are:');
put skip edit (A) (f(3));
/* Merges elements of SORTED with elements of TEMP and places */
/* the result in SORTED. */
/* Elements in SORTED and TEMP are in forward order. */
merge: procedure (sorted, temp);
declare (sorted, temp) fixed controlled;
declare work fixed controlled;
declare (j_ok, k_ok) bit (1);
do until ((k_ok | j_ok) = '0'b);
k_ok = allocation(sorted) > 0;
j_ok = allocation(temp) > 0;
if k_ok & j_ok then
do;
if sorted <= temp then
do; allocate work; work = sorted; free sorted; end;
else
do; allocate work; work = temp; free temp; end;
end;
else
if allocation(temp) = 0 then
/* temp is empty; copy remainder of sorted into work */
do while (allocation(sorted) > 0);
allocate work; work = sorted; free sorted;
end;
else
/* sorted is empty; copy remainder of temp onto work */
do while (allocation(temp) > 0);
allocate work; work = temp; free temp;
end;
end;
call move (sorted, work); /* Move the values to SORTED. */
end merge;
/* Collect a thread of ascending values from aray A, and stack them in temp. */
/* Note: the values in temp are in reverse order. */
fetch: procedure (A, temp);
declare A(*) fixed, temp controlled fixed;
declare i fixed binary;
do i = 1 to hbound(A,1);
if used(i) then
do; allocate temp; temp = A(i); used(i) = '0'b; go to found; end;
end;
found:
do i = i+1 to hbound(A,1);
if (temp <= A(i)) & used(i) then
do; allocate temp; temp = A(i); used(i) = '0'b; end;
end;
end fetch;
/* Copy the stack at TEMP to the stack at SORTED. */
/* In TEMP, elements are in reverse order; */
/* in SORTED, elements are in forward order. */
move: procedure (sorted, temp);
declare (sorted, temp) fixed controlled;
do while (allocation(sorted) > 0); free sorted; end;
do while (allocation (temp) > 0);
allocate sorted; sorted = temp; free temp;
end;
end move;
end strand;</syntaxhighlight>
Generated data:
<pre>
43 5 79 16 90 48 29 73 29 19 77 59 49 2 54 35 39 71 25 76 34 48 31 91 28 13 23 70 27 59 96 7 63 82 59 81 28 96 34 43
81 98 21 47 72 57 45 64 94 51 18 11 65 12 61 97 13 84 95 89 43 8 14 31 58 68 58 39 59 26 72 38 26 85 30 89 42 90 29 11
14 63 97 60 1 17 45 42 62 29 45 15 69 11 29 25 11 48 92 3
</pre>
Results:
<pre>
The sorted values are:
1 2 3 5 7 8 11 11 11 11 12 13 13 14 14 15 16 17 18 19 21 23 25 25 26 26 27 28 28 29 29 29 29 29 30 31 31 34 34 35
38 39 39 42 42 43 43 43 45 45 45 47 48 48 48 49 51 54 57 58 58 59 59 59 59 60 61 62 63 63 64 65 68 69 70 71 72 72 73 76
77 79 81 81 82 84 85 89 89 90 90 91 92 94 95 96 96 97 97 98
</pre>
=={{header|PureBasic}}==
<syntaxhighlight lang="purebasic">Procedure strandSort(List a())
Protected NewList subList()
Protected NewList results()
While ListSize(a()) > 0
ClearList(subList())
AddElement(subList())
FirstElement(a())
subList() = a()
DeleteElement(a())
ForEach a()
If a() >= subList()
AddElement(subList())
subList() = a()
DeleteElement(a())
EndIf
Next
;merge lists
FirstElement(subList())
If Not FirstElement(results())
;copy all of sublist() to results()
MergeLists(subList(), results(), #PB_List_Last)
Else
Repeat
If subList() < results()
InsertElement(results())
results() = subList()
DeleteElement(subList())
If Not NextElement(subList())
Break
EndIf
ElseIf Not NextElement(results())
;add remainder of sublist() to end of results()
MergeLists(subList(), results(), #PB_List_Last)
Break
EndIf
ForEver
EndIf
Wend
CopyList(results(), a())
EndProcedure
Procedure.s listContents(List a())
Protected output.s
PushListPosition(a())
ForEach a()
output + Str(a()) + ","
Next
PopListPosition(a())
ProcedureReturn Left(output, Len(output) - 1)
EndProcedure
Procedure setupList(List a())
ClearList(a())
Protected elementCount, i
elementCount = Random(5) + 10
For i = 1 To elementCount
AddElement(a())
a() = Random(10) - 5
Next
EndProcedure
If OpenConsole()
NewList sample()
Define i
For i = 1 To 3
setupList(sample())
PrintN("List " + Str(i) + ":")
PrintN(" Before: " + listContents(sample()))
strandSort(sample())
PrintN(" After : " + listContents(sample()))
PrintN("")
Next
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf</syntaxhighlight>
Sample output:
<pre>List 1:
Before: 3,-2,-4,4,-1,-3,-2,-2,2,2,0
After : -4,-3,-2,-2,-2,-1,0,2,2,3,4
List 2:
Before: -4,4,3,-2,3,-2,5,0,-1,0,5,1
After : -4,-2,-2,-1,0,0,1,3,3,4,5,5
List 3:
Before: -2,0,-2,5,5,3,-1,-3,5,5,0,2,-4,4,2
After : -4,-3,-2,-2,-1,0,0,2,2,3,4,5,5,5,5</pre>
=={{header|Python}}==
<syntaxhighlight lang="python">def merge_list(a, b):
out = []
while len(a) and len(b):
if a[0] < b[0]:
out.append(a.pop(0))
else:
out.append(b.pop(0))
out += a
out += b
return out
def strand(a):
i, s = 0, [a.pop(0)]
while i < len(a):
if a[i] > s[-1]:
s.append(a.pop(i))
else:
i += 1
return s
def strand_sort(a):
out = strand(a)
while len(a):
out = merge_list(out, strand(a))
return out
print strand_sort([1, 6, 3, 2, 1, 7, 5, 3])</syntaxhighlight>
Output:<syntaxhighlight lang="text">[1, 1, 2, 3, 3, 5, 6, 7]</syntaxhighlight>
=={{header|Quackery}}==
<syntaxhighlight lang="Quackery"> [ [] swap
1 split witheach
[ over -1 peek
over > iff
[ swap dip join ]
else join ] ] is sift ( [ --> [ [ )
[ [] temp put
[ dup [] != while
over [] != while
over 0 peek
over 0 peek
> not if dip
[ behead
temp take
swap join
temp put ]
again ]
join
temp take swap join ] is merge ( [ [ --> [ )
[ [] swap
[ sift
rot merge swap
dup [] = until ]
drop ] is strandsort ( [ --> [ )
[] 25 times
[ 89 random 10 + join ]
say "Before: " dup echo cr
strandsort
say "After: " echo cr</syntaxhighlight>
{{out}}
<pre>Before: [ 46 66 79 51 21 79 65 46 95 17 92 13 32 11 72 44 83 64 50 88 46 38 57 37 27 ]
After: [ 11 13 17 21 27 32 37 38 44 46 46 46 50 51 57 64 65 66 72 79 79 83 88 92 95 ]</pre>
=={{header|Racket}}==
<syntaxhighlight lang="racket">
#lang racket
(require mzlib/list)
(define (merge xs ys) (merge-sorted-lists xs ys <=))
(define (strand-sort xs)
(let loop ([xs xs] [ys '[]])
(cond [(empty? xs) ys]
[else (define-values (sorted unsorted) (extract-strand xs))
(loop unsorted (merge sorted ys))])))
(define (extract-strand xs)
(for/fold ([strand '()] [unsorted '[]]) ([x xs])
(if (or (empty? strand) (< x (first strand)))
(values (cons x strand) unsorted)
(values strand (cons x unsorted)))))
(strand-sort (build-list 10 (λ(_) (random 15))))
</syntaxhighlight>
=={{header|Raku}}==
(formerly Perl 6)
{{Works with|Rakudo|2018.04.01}}
<syntaxhighlight lang="raku" line>sub infix:<M> (@x-in, @y-in) {
my @x = | @x-in;
my @y = | @y-in;
flat @x, @y,
reverse gather while @x and @y {
take do given @x[*-1] cmp @y[*-1] {
when More { pop @x }
when Less { pop @y }
when Same { pop(@x), pop(@y) }
}
}
}
sub strand (@x) {
my $i = 0;
my $prev = -Inf;
gather while $i < @x {
@x[$i] before $prev ?? $i++ !! take $prev = splice(@x, $i, 1)[0];
}
}
sub strand_sort (@x is copy) {
my @out;
@out M= strand(@x) while @x;
@out;
}
my @a = (^100).roll(10);
say "Before {@a}";
@a = strand_sort(@a);
say "After {@a}";
@a = <The quick brown fox jumps over the lazy dog>;
say "Before {@a}";
@a = strand_sort(@a);
say "After {@a}";</syntaxhighlight>
{{out}}
<pre>Before 1 20 64 72 48 75 96 55 42 74
After 1 20 42 48 55 64 72 74 75 96
Before The quick brown fox jumps over the lazy dog
After The brown dog fox jumps lazy over quick the</pre>
=={{header|REXX}}==
This REXX program was written to generate a specified amount of random numbers as
well as allowing a pre-pended list of items).
It can handle integers, floating point numbers, exponentiated numbers, and/or character strings.
<syntaxhighlight lang="rexx">/*REXX program sorts a random list of words (or numbers) */
/* using the strand sort algorithm */
Parse Arg size minv maxv old /* obtain optional arguments from CL*/
if size=='' | size=="," then size=20 /*Not specified? use default.*/
if minv=='' | minv=="," then minv= 0 /*Not specified? use default.*/
if maxv=='' | maxv=="," then maxv=size /*Not specified? use default.*/
Do i=1 To size
old=old random(0,maxv-minv)+minv/* append random numbers to the list*/
End
old=space(old)
Say 'Unsorted list:'
Say old
new=strand_sort(old) /* sort given list (extended by random numbers) */
Say
Say 'Sorted list:'
Say new
Exit /* stick a fork in it, we're all done */
/*--------------------------------------------------------------------*/
strand_sort: Procedure
Parse Arg source
sorted=''
Do While words(source)\==0
w=words(source)
/* Find first word in source that is smaller Than its predecessor */
Do j=1 To w-1
If word(source,j)>word(source,j+1) Then
Leave
End
/* Elements source.1 trough source.j are in ascending order */
head=subword(source,1,j)
source=subword(source,j+1) /* the rest starts with a smaller */
/* value or is empty (j=w!) */
sorted=merge(sorted,head)
End
Return sorted
/*--------------------------------------------------------------------*/
merge: Procedure
Parse Arg a.1,a.2
p=''
Do Forever
w1=words(a.1)
w2=words(a.2)
Select
When w1==0 | w2==0 Then
Return space(p a.1 a.2)
When word(a.1,w1)<=word(a.2,1) Then
Return space(p a.1 a.2)
When word(a.2,w2)<=word(a.1,1) Then
Return space(p a.2 a.1)
Otherwise Do
nn=1+(word(a.1,1)>=word(a.2,1))
/* move the smaller first word of a.1 or a.2 to p */
p=p word(a.nn,1)
a.nn=subword(a.nn,2)
End
End
End</syntaxhighlight>
'''output''' when using the input of: <tt> 25 -9 30 1000 2000 3000 </tt>
<pre>
────────────────────────────────unsorted list────────────────────────────────
1000 2000 3000 9 0 3 -8 17 8 -2 4 0 -3 19 -1 3 1 8 27 14 20 2 -6 23 1 -8 -4 4
─────────────────────────────────sorted list─────────────────────────────────
-8 -8 -6 -4 -3 -2 -1 0 0 1 1 2 3 3 4 4 8 8 9 14 17 19 20 23 27 1000 2000 3000
</pre>
The REXX program can also sort words as well as numbers. <br>
<br>'''output''' when using the input of: <tt> 24 -9 100 66 66 8.8 carp Carp </tt>
<pre>
──────────────────────────────────────unsorted list───────────────────────────────────────
66 66 8.8 carp Carp 20 77 88 9 39 -5 10 12 80 87 26 61 87 94 73 27 49 35 95 81 76 40 13 72
───────────────────────────────────────sorted list────────────────────────────────────────
-5 8.8 9 10 12 13 20 26 27 35 39 40 49 61 66 66 72 73 76 77 80 81 87 87 88 94 95 Carp carp
</pre>
Note that an ASCII computer will sort words differently than an EBCDIC machine. <br>
<br>The order of sorting on an ASCII machine is: <tt> numbers, upperCase, lowerCase </tt>
<br>The order of sorting on an EBCDIC machine is: <tt> lowerCase, upperCase, numbers </tt>
<br><br>
=={{header|Ring}}==
<syntaxhighlight lang="ring">
# Project : Sorting algorithms/Strand sort
test = [-2,0,-2,5,5,3,-1,-3,5,5,0,2,-4,4,2]
results = []
resultsend = []
see "before sort:" + nl
showarray(test)
test = strandsort(test)
see "after sort:" + nl
showarray(test)
func strandsort(a)
while len(a) > 0
sublist = []
add(sublist,a[1])
del(a,1)
for i = 1 to len(a)
if a[i] > sublist[len(sublist)]
add(sublist,a[i])
del(a,i)
ok
next
for n = 1 to len(sublist)
add(results,sublist[n])
next
for n = 1 to len(results)
for m = n + 1 to len(results)
if results[m] < results[n]
temp = results[m]
results[m] = results[n]
results[n] = temp
ok
next
next
end
return results
func showarray(vect)
svect = ""
for n = 1 to len(vect)
svect = svect + vect[n] + " "
next
svect = left(svect, len(svect) - 1)
see svect + nl
</syntaxhighlight>
Output:
<pre>
before sort:
-2 0 -2 5 5 3 -1 -3 5 5 0 2 -4 4 2
after sort:
-4 -3 -2 -2 -1 0 0 2 2 3 4 5 5 5 5
</pre>
=={{header|Ruby}}==
<syntaxhighlight lang="ruby">class Array
def strandsort
a = dup
result = []
until a.empty?
v = a.first
sublist, a = a.partition{|val| v=val if v<=val} # In case of v>val, it becomes nil.
result.each_index do |idx|
break if sublist.empty?
result.insert(idx, sublist.shift) if sublist.first < result[idx]
end
result += sublist
end
result
end
def strandsort!
replace(strandsort)
end
end
p [1, 6, 3, 2, 1, 7, 5, 3].strandsort</syntaxhighlight>
{{out}}
<pre>[1, 1, 2, 3, 3, 5, 6, 7]</pre>
=={{header|Sidef}}==
{{trans|Perl}}
<syntaxhighlight lang="ruby">func merge(x, y) {
var out = [];
while (x && y) {
given (x[-1] <=> y[-1]) {
when ( 1) { out.prepend(x.pop) }
when (-1) { out.prepend(y.pop) }
default { out.prepend(x.pop, y.pop) }
}
}
x + y + out;
}
func strand(x) {
x || return [];
var out = [x.shift];
if (x.len) {
for i in (-x.len .. -1) {
if (x[i] >= out[-1]) {
out.append(x.pop_at(i));
}
}
}
return out;
}
func strand_sort(x) {
var out = [];
while (var strd = strand(x)) {
out = merge(out, strd);
}
return out;
}
var a = 10.of { 100.irand };
say "Before: #{a}";
say "After: #{strand_sort(a)}";</syntaxhighlight>
{{out}}
<pre>
Before: 24 62 29 95 11 21 46 3 23 20
After: 3 11 20 21 23 24 29 46 62 95
</pre>
=={{header|Tcl}}==
<
upvar 1 $listVar v
set i [set j 0]
Line 146 ⟶ 2,040:
}
puts [strandSort {3 1 5 4 2}]</
=={{header|Ursala}}==
<syntaxhighlight lang="ursala">strand_sort "r" = # parameterized by a relational predicate "r"
@NiX -+
:-0 ~&B^?a\~&Y@a "r"?abh/~&alh2faltPrXPRC ~&arh2falrtPXPRC,
~&r->l ^|rlPlCrrPX/~& @hNCNXtX ~&r->lbx "r"?rllPXh/~&llPrhPlrPCXrtPX ~&rhPllPClrPXrtPX+-</syntaxhighlight>
demonstration code:<syntaxhighlight lang="ursala">#cast %nL
x = (strand_sort nat-nleq) <3,1,5,4,2></syntaxhighlight>output:<pre><1,2,3,4,5></pre>
=={{header|Wren}}==
{{trans|Kotlin}}
<syntaxhighlight lang="wren">var merge = Fn.new { |left, right|
var res = []
while (!left.isEmpty && !right.isEmpty) {
if (left[0] <= right[0]) {
res.add(left[0])
left.removeAt(0)
} else {
res.add(right[0])
right.removeAt(0)
}
}
res.addAll(left)
res.addAll(right)
return res
}
var strandSort = Fn.new { |a|
var list = a.toList
var res = []
while (!list.isEmpty) {
var sorted = [list[0]]
list.removeAt(0)
var leftover = []
for (item in list) {
if (sorted[-1] <= item) {
sorted.add(item)
} else {
leftover.add(item)
}
}
res = merge.call(sorted, res)
list = leftover
}
return res
}
var a = [-2, 0, -2, 5, 5, 3, -1, -3, 5, 5, 0, 2, -4, 4, 2]
System.print("Unsorted: %(a)")
a = strandSort.call(a)
System.print("Sorted : %(a)")</syntaxhighlight>
{{out}}
<pre>
Unsorted: [-2, 0, -2, 5, 5, 3, -1, -3, 5, 5, 0, 2, -4, 4, 2]
Sorted : [-4, -3, -2, -2, -1, 0, 0, 2, 2, 3, 4, 5, 5, 5, 5]
</pre>
=={{header|zkl}}==
<syntaxhighlight lang="zkl">fcn strandSort(A){ //--> new list, A is cleared, should add A=A.copy()
sublist:=List.createLong(A.len()); results:=List.createLong(A.len());
while(A){
sublist.clear(A.pop(0));
foreach i in (A.len() - 1){
if(A[i]>sublist[-1]) sublist.append(A.pop(i));
}
results.merge(sublist);
}
results
}</syntaxhighlight>
The createLong list method creates a new list with pre-allocated space
<syntaxhighlight lang="zkl">strandSort(L(3,1,5,4,2)).println();
strandSort("azbfe".split("")).println();</syntaxhighlight>
{{out}}
<pre>
L(1,2,3,4,5)
L("a","b","e","f","z")
</pre>
{{omit from|GUISS}}
| |||