Sorting Algorithms/Circle Sort: Difference between revisions

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comprehensive odd list length test inserted.
(added FreeBASIC)
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{{draft task|Sorting Algorithms}}{{Sorting Algorithm}}
Sort an array of integers (of any convenient size) into ascending order using Circlesort. In short, compare the first element to the last element, then the second element to the second last element, etc. Then split the array in two and recurse until there is only one single element in the array, like this:
 
Sort an array of integers (of any convenient size) into ascending order using Circlesort.
 
In short, compare the first element to the last element, then the second element to the second last element, etc.
 
Then split the array in two and recurse until there is only one single element in the array, like this:
Before:
'''6''' ''7'' 8 9 2 5 3 ''4'' '''1'''
Line 11 ⟶ 6:
'''1''' ''4'' 3 5 2 9 8 ''7'' '''6'''
 
Show both the initial, unsorted list and the final sorted list. (Intermediate steps during sorting are optional.) Optimizations (like doing ''0.5 log2(n)'' iterations and then continue with an [[Insertion sort]]) are optional.
Repeat this procedure until quiescence (i.e. until there are no swaps).
 
Show both the initial, unsorted list and the final sorted list. (Intermediate steps during sorting are optional.)
 
Optimizations (like doing ''0.5 log2(n)'' iterations and then continue with an [[Insertion sort]]) are optional. <br>
 
Pseudo code:
Line 44 ⟶ 35:
'''while''' circlesort (0, '''sizeof'''(array)-1, 0)
 
For more information on Circle sorting, see [http://sourceforge.net/p/forth-4th/wiki/Circle%20sort/ Sourceforge].
 
__FORCETOC__
;See also:
* For more information on Circle sorting, see [http://sourceforge.net/p/forth-4th/wiki/Circle%20sort/ Sourceforge].
<br><br>
 
=={{header|C}}==
<lang c>#include <stdio.h>
 
int circle_sort_innercir_sort_inner(int *startx, int *endn)
{
int *pi, *qj, t, swappedswaps;
 
if (startn ==< end2) return 0;
 
for (swaps = i = 0, j = n - 1; i < j; i++, j--)
// funny "||" on next line is for the center element of odd-lengthed array
if (x[i] > x[j])
for (swapped = 0, p = start, q = end; p<q || (p==q && ++q); p++, q--)
t=x[i], x[i]=x[j], x[j]=t, swaps++;
if (*p > *q)
t = *p, *p = *q, *q = t, swapped = 1;
 
return swaps + cir_sort_inner(x, j + 1) + cir_sort_inner(x + i, n - i);
// q == p-1 at this point
return swapped | circle_sort_inner(start, q) | circle_sort_inner(p, end);
}
 
//helper function to show arrays before each call
void circle_sortcir_sort(int *x, int n)
{
int i, s;
 
do {
for (i = 0; i < n; i++)
int i;
for (i = 0; i < n; i++) printf("%d ", x[i]);
printf(": %d swaps\n", s = cir_sort_inner(x, n));
putchar('\n');
} while (circle_sort_inner(x, x + (n - 1))s);
}
 
int main(void)
{
int x[] = { 5, -1, 101, -4, 0, 1, 8, 6, 2, 3 };
circle_sortcir_sort(x, sizeof(x) / sizeof(*x[0]));
 
return 0;
Line 86 ⟶ 75:
{{out}}
<pre>
5 -1 101 -4 0 1 8 6 2 3 : 9 swaps
-4 0 -1 0 3 6 1 2 8 5 8 101 : 6 swaps
-4 -1 0 1 2 3 5 6 8 101 : 0 swaps
</pre>
 
Line 183 ⟶ 172:
console: -1,0,1,3,2,5,4,8,6,7,9,12,10,11,13,14
console: -1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14</pre>
 
=={{header|Elixir}}==
<lang elixir>defmodule Sort do
def circle_sort(data) do
List.to_tuple(data)
|> circle_sort(0, length(data)-1)
|> Tuple.to_list
end
defp circle_sort(data, lo, hi) do
case circle_sort(data, lo, hi, 0) do
{result, 0} -> result
{result, _} -> circle_sort(result, lo, hi)
end
end
defp circle_sort(data, lo, lo, swaps), do: {data, swaps}
defp circle_sort(data, lo, hi, swaps) do
mid = div(lo + hi, 2)
{data, swaps} = do_circle_sort(data, lo, hi, swaps)
{data, swaps} = circle_sort(data, lo, mid, swaps)
circle_sort(data, mid+1, hi, swaps)
end
def do_circle_sort(data, lo, hi, swaps) when lo>=hi do
if lo==hi and elem(data, lo) > elem(data, hi+1),
do: {swap(data, lo, hi+1), swaps+1},
else: {data, swaps}
end
def do_circle_sort(data, lo, hi, swaps) do
if elem(data, lo) > elem(data, hi),
do: do_circle_sort(swap(data, lo, hi), lo+1, hi-1, swaps+1),
else: do_circle_sort(data, lo+1, hi-1, swaps)
end
defp swap(data, i, j) do
vi = elem(data, i)
vj = elem(data, j)
data |> put_elem(i, vj) |> put_elem(j, vi)
end
end
 
data = [6, 7, 8, 9, 2, 5, 3, 4, 1]
IO.puts "before sort: #{inspect data}"
IO.puts " after sort: #{inspect Sort.circle_sort(data)}"</lang>
 
{{out}}
<pre>
before sort: [6, 7, 8, 9, 2, 5, 3, 4, 1]
after sort: [1, 2, 3, 4, 5, 6, 7, 8, 9]
</pre>
 
=={{header|Forth}}==
<lang>defer precedes ( addr addr -- flag )
This one features the newest version of the algorithm on [http://sourceforge.net/p/forth-4th/wiki/Circle%20sort/ Sourceforge].
variable (swaps) \ keeps track of swaps
<lang>[UNDEFINED] cell- [IF] : cell- 1 cells - ; [THEN]
 
[UNDEFINED] cell- [IF] : cell- 1 cells - ; [THEN]
defer precedes ( addr addr -- flag )
variable (sorted?) \ is the array sorted?
 
: (compare) ( a1 a2 -- a1 a2)
over @ over @ precedes \ flag if swapped, increment (swaps)
if over over over @ over @ swap rot ! swap ! false1 (sorted?swaps) +! then
;
 
: (circlesort) ( a1a a2n --)
dup 1 > if
over over = if drop drop exit then \ quit if indexes are equal
over over swap \ swap indexes (end beginarray len)
1- cells over + swap ( 'end 'begin)
begin
begin
over over > \ as long as middle isn't passed
over over > \ if we didn't pass the middle
while
(compare)while swap cell- swap cell+ \ check and swap opposite elements
(compare) swap cell- swap cell+
repeat rot recurse recurse \ split array and recurse
repeat \ check if there's a middle element
over over = if cell- (compare) then drop drop
over over 2/ recurse \ sort first partition
dup 2/ cells rot + swap dup 2/ - recurse exit
then \ sort second partition
drop drop \ nothing to sort
;
 
: sort begin 0 (swaps) ! over over (circlesort) (swaps) @ 0= until drop drop ;
: sort ( a n --)
1- cells over + \ calculate addresses
begin true (sorted?) ! over over (circlesort) (sorted?) @ until drop drop
;
 
:noname < ; is precedes
 
10 constant /sample
create sample 5 , -1 , 101 , -4 , 0 , 1 , 8 , 6 , 2 , 3 ,
 
: .sample sample /sample cells bounds do i ? 1 cells +loop ;
 
sample /sample sort .sample</lang>
=={{header|FreeBASIC}}==
<lang freebasic>' version 21-10-2016
' compile with: fbc -s console
' for boundry checks on array's compile with: fbc -s console -exx
' converted pseudo code into FreeBASIC code
 
' shared variables need to be declared before first use
Dim Shared As Long cs(-7 To 7)
 
Function circlesort(lo As Long, hi As Long, swaps As ULong) As ULong
 
' array is declared shared
' sort from lower bound to the highter bound
' array's can have subscript range from -2147483648 to +2147483647
 
If lo = hi Then Return swaps
 
Dim As Long high = hi
Dim As Long low = lo
Dim As Long mid_ = (hi - lo) \ 2
 
While lo < hi
If cs(lo) > cs(hi) Then
Swap cs(lo), cs(hi)
swaps += 1
End If
lo += 1
hi -= 1
Wend
If lo = hi Then
If cs(lo) > cs(hi +1) Then
Swap cs(lo), cs(hi +1)
swaps += 1
End If
End If
swaps = circlesort(low , low + mid_, swaps)
swaps = circlesort(low + mid_ +1, high, swaps)
 
Return swaps
 
End Function
 
' ------=< MAIN >=------
 
Dim As Long i, a = LBound(cs), b = UBound(cs)
 
Randomize Timer
For i = a To b : cs(i) = i : Next
For i = a To b ' little shuffle
Swap cs(i), cs(Int(Rnd * (b - a +1)) + a)
Next
 
Print "unsorted ";
For i = a To b : Print Using "####"; cs(i); : Next : Print
 
' sort the array, loop until sorted
While circlesort(a, b, 0) : Wend
 
Print " sorted ";
For i = a To b : Print Using "####"; cs(i); : Next : Print
 
' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End</lang>
{{out}}
<pre>unsorted -4 -1 1 0 5 -7 -2 4 -6 -3 2 6 3 7 -5
sorted -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7</pre>
 
=={{header|J}}==
Of more parsing and atomic data, or less parsing with large data groups the latter produces faster J programs. Consequently each iteration laminates the original with its reverse. It joins the recursive call to the pairwise minima of the left block to the recursive call of the pairwise maxima of the right block, repeating the operations while the output changes. This is sufficient for power of 2 length data. The pre verb adjusts the data length. And post recovers the original data. This implementation discards the "in place" property described at the sourceforge link.
 
<lang J>
circle_sort =: post power_of_2_length@pre NB. the main sorting verb
power_of_2_length =: even_length_iteration^:_ NB. repeat while the answer changes
even_length_iteration =: (<./ (,&$: |.) >./)@(-:@# ({. ,: |.@}.) ])^:(1<#)
pre =: , (-~ >.&.(2&^.))@# # >./ NB. extend data to next power of 2 length
post =: ({.~ #)~ NB. remove the extra data
</lang>
Examples:
<lang J>
show =: [ smoutput
 
8 ([: circle_sort&.>@show ;&(?~)) 13 NB. sort lists length 8 and 13
┌───────────────┬────────────────────────────┐
│0 6 7 3 4 5 2 1│3 10 1 4 7 8 5 6 2 0 9 11 12│
└───────────────┴────────────────────────────┘
┌───────────────┬────────────────────────────┐
│0 1 2 3 4 5 6 7│0 1 2 3 4 5 6 7 8 9 10 11 12│
└───────────────┴────────────────────────────┘
8 ([: circle_sort&.>@show ;&(1 }. 2 # ?~)) 13 NB. data has repetition
┌─────────────────────────────┬──────────────────────────────────────────────────────┐
│2 3 3 5 5 1 1 7 7 6 6 4 4 0 0│12 11 11 4 4 3 3 9 9 7 7 10 10 6 6 2 2 1 1 5 5 8 8 0 0│
└─────────────────────────────┴──────────────────────────────────────────────────────┘
┌─────────────────────────────┬──────────────────────────────────────────────────────┐
│0 0 1 1 2 3 3 4 4 5 5 6 6 7 7│0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12│
└─────────────────────────────┴──────────────────────────────────────────────────────┘
</lang>
 
=={{header|Java}}==
<lang java>import java.util.Arrays;
 
public class CircleSort {
 
public static void main(String[] args) {
circleSort(new int[]{2, 14, 4, 6, 8, 1, 3, 5, 7, 11, 0, 13, 12, -1});
}
 
public static void circleSort(int[] arr) {
if (arr.length > 0)
do {
System.out.println(Arrays.toString(arr));
} while (circleSortR(arr, 0, arr.length - 1, 0) != 0);
}
 
private static int circleSortR(int[] arr, int lo, int hi, int numSwaps) {
if (lo == hi)
return numSwaps;
 
int high = hi;
int low = lo;
int mid = (hi - lo) / 2;
 
while (lo < hi) {
if (arr[lo] > arr[hi]) {
swap(arr, lo, hi);
numSwaps++;
}
lo++;
hi--;
}
 
if (lo == hi && arr[lo] > arr[hi + 1]) {
swap(arr, lo, hi + 1);
numSwaps++;
}
 
numSwaps = circleSortR(arr, low, low + mid, numSwaps);
numSwaps = circleSortR(arr, low + mid + 1, high, numSwaps);
 
return numSwaps;
}
 
private static void swap(int[] arr, int idx1, int idx2) {
int tmp = arr[idx1];
arr[idx1] = arr[idx2];
arr[idx2] = tmp;
}
}</lang>
 
<pre>[2, 14, 4, 6, 8, 1, 3, 5, 7, 11, 0, 13, 12, -1]
[-1, 1, 0, 4, 3, 8, 12, 2, 7, 6, 11, 5, 13, 14]
[-1, 0, 1, 3, 2, 4, 7, 5, 6, 8, 12, 11, 13, 14]
[-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13, 14]</pre>
 
=={{header|jq}}==
{{works with|jq|1.4}}
 
With kudos to [[#Perl 6]].
 
"circlesort" as defined in this section can be used to sort any JSON array. In case your jq does not have "until" as a builtin, here is its definition:
<lang jq>def until(cond; next):
def _until: if cond then . else (next|_until) end;
_until;</lang>
<lang jq>def circlesort:
 
def swap(i;j): .[i] as $t | .[i] = .[j] | .[j] = $t;
 
# state: [lo, hi, swaps, array]
def cs:
 
# increment lo, decrement hi, and if they are equal, increment hi again
# i.e. ++hi if --hi == $lo
def next: # [lo, hi]
.[0] += 1 | .[1] -= 1 | (if .[0] == .[1] then .[1] += 1 else . end) ;
 
.[0] as $start | .[1] as $stop
| if $start < $stop then
until(.[0] >= .[1];
.[0] as $lo | .[1] as $hi | .[3] as $array
| if $array[$lo] > $array[$hi] then
.[3] = ($array | swap($lo; $hi))
| .[2] += 1 # swaps++
else .
end
| next)
| .[0] as $lo | .[1] as $hi
| [$start, $hi, .[2], .[3]] | cs
| [$lo, $stop, .[2], .[3]] | cs
else .
end ;
 
[0, length-1, 0, .] | cs
| .[2] as $swaps
| .[3]
| if $swaps == 0 then .
else circlesort
end ;</lang>
'''Example:'''
<lang jq>"The quick brown fox jumps over the lazy dog" | split(" ") | circlesort</lang>
 
{{out}}
<lang sh>$ jq -n -c -f -M circleSort.jq
["The","brown","dog","fox","jumps","lazy","over","quick","the"]</lang>
 
=={{header|PARI/GP}}==
This follows the pseudocode pretty closely.
<lang parigp>circlesort(v)=
{
local(v=v); \\ share with cs
while (cs(1, #v),);
v;
}
cs(lo, hi)=
{
if (lo == hi, return (0));
my(high=hi,low=lo,mid=(hi-lo)\2,swaps);
while (lo < hi,
if (v[lo] > v[hi],
[v[lo],v[hi]]=[v[hi],v[lo]];
swaps++
);
lo++;
hi--
);
if (lo==hi && v[lo] > v[hi+1],
[v[lo],v[hi+1]]=[v[hi+1],v[lo]];
swaps++
);
swaps + cs(low,low+mid) + cs(low+mid+1,high);
}
print(example=[6,7,8,9,2,5,3,4,1]);
print(circlesort(example));</lang>
{{out}}
<pre>[6, 7, 8, 9, 2, 5, 3, 4, 1]
[1, 2, 3, 4, 5, 6, 7, 8, 9]</pre>
 
=={{header|Perl 6}}==
The given algorithm can be simplified in several ways. There's no need to compute the midpoint, since the hi/lo will end up there. The extra swap conditional can be eliminated by incrementing hi at the correct moment inside the loop. There's no need to
pass accumulated swaps down the call stack.
 
This does generic comparisons, so it works on any ordered type, including numbers or strings.
<lang perl6>sub circlesort (@x, $beg, $end) {
my $swaps = 0;
if $beg < $end {
my ($lo, $hi) = $beg, $end;
repeat {
if @x[$lo] after @x[$hi] {
@x[$lo,$hi] .= reverse;
++$swaps;
}
++$hi if --$hi == ++$lo
} while $lo < $hi;
$swaps += circlesort(@x, $beg, $hi);
$swaps += circlesort(@x, $lo, $end);
}
$swaps;
}
 
say my @x = (-100..100).roll(20);
say @x while circlesort(@x, 0, @x.end);
 
say @x = <The quick brown fox jumps over the lazy dog.>;
say @x while circlesort(@x, 0, @x.end);</lang>
{{out}}
<pre>16 35 -64 -29 46 36 -1 -99 20 100 59 26 76 -78 39 85 -7 -81 25 88
-99 -78 16 20 36 -81 -29 46 25 59 -64 -7 39 26 88 -1 35 85 76 100
-99 -78 -29 -81 16 -64 -7 20 -1 39 25 26 36 46 59 35 76 88 85 100
-99 -81 -78 -64 -29 -7 -1 16 20 25 26 35 36 39 46 59 76 85 88 100
The quick brown fox jumps over the lazy dog.
The brown fox jumps lazy dog. quick over the
The brown dog. fox jumps lazy over quick the</pre>
 
=={{header|Python}}==
The doctest passes with odd and even length lists. As do the random tests. Please see circle_sort.__doc__ for example use and output.
<lang python>
#python3
Line 555 ⟶ 221:
def circle_sort_backend(A:list, L:int, R:int)->'sort A in place, returning the number of swaps':
'''
>>> Limport = [3, 2, 8, 28, 2,]itertools
>>> circle_sortLR7 = list(Lrange(7))
>>> for T in itertools.permutations(LR7):
3
>>>... print(L = list(T)
[2,... 2, 3, 8, 28] junk = circle_sort(L)
... if L != LR7:
... print(L)
...
>>> L = [3, 2, 8, 28,]
>>> circle_sort(L)
Line 602 ⟶ 271:
print(L)
</lang>
 
=={{header|Racket}}==
 
By default this sorts with the numeric <code>&lt;</code> but any other
(diadic) function can be used to compare... e.g. <code>string&lt;?</code>.
 
<lang racket>#lang racket
(define (circle-sort v0 [<? <])
(define v (vector-copy v0))
 
(define (swap-if l r)
(define v.l (vector-ref v l))
(define v.r (vector-ref v r))
(and (<? v.r v.l)
(begin (vector-set! v l v.r) (vector-set! v r v.l) #t)))
 
(define (inr-cs! L R)
(cond
[(>= L (- R 1)) #f] ; covers 0 or 1 vectors
[else
(define M (quotient (+ L R) 2))
(define I-moved?
(for/or ([l (in-range L M)] [r (in-range (- R 1) L -1)])
(swap-if l r)))
(define M-moved? (and (odd? (- L R)) (> M 0) (swap-if (- M 1) M)))
(define L-moved? (inr-cs! L M))
(define R-moved? (inr-cs! M R))
(or I-moved? L-moved? R-moved? M-moved?)]))
 
(let loop () (when (inr-cs! 0 (vector-length v)) (loop)))
v)
 
(define (sort-random-vector)
(define v (build-vector (+ 2 (random 10)) (λ (i) (random 100))))
(define v< (circle-sort v <))
(define sorted? (apply <= (vector->list v<)))
(printf " ~.a\n-> ~.a [~a]\n\n" v v< sorted?))
 
(for ([_ 10]) (sort-random-vector))
 
(circle-sort '#("table" "chair" "cat" "sponge") string<?)</lang>
 
{{out}}
<pre>
#(36 94 63 51 33)
-> #(33 36 51 63 94) [#t]
 
#(73 74 20 20 79)
-> #(20 20 73 74 79) [#t]
 
#(83 42)
-> #(42 83) [#t]
 
#(53 95 43 33 66 47 1 61 28 96)
-> #(1 28 33 43 47 53 61 66 95 96) [#t]
 
#(71 85)
-> #(71 85) [#t]
 
#(36 85 50 19 88 17 2 53 21)
-> #(2 17 19 21 36 50 53 85 88) [#t]
 
#(5 97 62 21 99 73 17 16 37 28)
-> #(5 16 17 21 28 37 62 73 97 99) [#t]
 
#(12 60 89 90 2 95 9 28)
-> #(2 9 12 28 60 89 90 95) [#t]
 
#(50 32 30 47 63 74)
-> #(30 32 47 50 63 74) [#t]
 
#(63 41)
-> #(41 63) [#t]
 
'#("cat" "chair" "sponge" "table")
</pre>
 
=={{header|REXX}}==
This REXX version will work with any numbers that REXX supports, including negative and/or floating point numbers.
<lang rexx>/*REXX program uses a circle sort algorithm to sort an array (or list) of numbers. */
parse arg x /*obtain optional arguments from the CL*/
if x='' | x="," then x= 6 7 8 9 2 5 3 4 1 /*Not specified? Then use the default.*/
call make_array 'before sort:' /*display the list and make an array. */
call circleSort # /*invoke the circle sort subroutine. */
call make_list ' after sort:' /*make a list and display it to console*/
exit /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
circleSort: do while .circleSrt(1, arg(1), 0)\==0; end; return
make_array: #=words(x); do i=1 for #; @.i=word(x, i); end; say arg(1) x; return
make_list: y=@.1; do j=2 to #; y=y @.j; end; say arg(1) y; return
.swap: parse arg a,b; parse value @.a @.b with @.b @.a; swaps=swaps+1; return
/*──────────────────────────────────────────────────────────────────────────────────────*/
.circleSrt: procedure expose @.; parse arg lo,hi,swaps /*obtain LO & HI arguments.*/
if lo==hi then return swaps /*1 element? Done with sort.*/
high=hi; low=lo; mid=(hi-lo) % 2 /*assign some indices. */
/* [↓] sort a section of #'s*/
do while lo<hi /*sort within a section. */
if @.lo>@.hi then call .swap lo,hi /*are numbers out of order ? */
lo=lo+1; hi=hi-1 /*add to LO; shrink the HI. */
end /*while ··· */ /*just process one section. */
_=hi+1 /*point to HI plus one. */
if lo==hi & @.lo>@._ then call .swap lo, _ /*numbers still out of order?*/
swaps=.circleSrt(low, low+mid, swaps) /*sort the lower section. */
swaps=.circleSrt(low+mid+1, high, swaps) /* " " higher " */
return swaps /*the section sorting is done*/</lang>
'''output''' &nbsp; when using the default input:
<pre>
before sort: 6 7 8 9 2 5 3 4 1
after sort: 1 2 3 4 5 6 7 8 9
</pre>
'''output''' &nbsp; when using the input of: &nbsp; <tt> 2 3 3 5 5 1 1 7 7 6 6 4 4 0 0 </tt>
<pre>
before sort: 2 3 3 5 5 1 1 7 7 6 6 4 4 0 0
after sort: 0 0 1 1 2 3 3 4 4 5 5 6 6 7 7
</pre>
'''output''' &nbsp; when using the input of: &nbsp; <tt> 2 3 44 44 5.77 +1 -12345 -3 -3.9 1e7 9 </tt>
<pre>
before sort: 2 3 44 44 5.77 +1 -12345 -3 -3.9 1e7 0
before sort: -12345 -3.9 -3 0 +1 2 3 5.77 44 44 1e7
</pre>
'''output''' &nbsp; when using the input of: &nbsp; <tt> assinine donkey bovine cattle canine dog corvine crow equine horse feline cat hircine goat leporine hare lupine wolf murine rodent piscine fish porcine pig ursine bear vulpine fox </tt>
<pre>
before sort: assinine donkey bovine cattle canine dog corvine crow equine horse feline cat hircine goat leporine hare lupine wolf murine rodent piscine fish porcine pig ursine bear vulpine fox
after sort: assinine bear bovine canine cat cattle corvine crow dog donkey equine feline fish fox goat hare hircine horse leporine lupine murine pig piscine porcine rodent ursine vulpine wolf
</pre>
 
=={{header|Ruby}}==
<lang ruby>class Array
def circle_sort!
while _circle_sort!(0, size-1) > 0
end
self
end
private
def _circle_sort!(lo, hi, swaps=0)
return swaps if lo == hi
low, high = lo, hi
mid = (lo + hi) / 2
while lo < hi
if self[lo] > self[hi]
self[lo], self[hi] = self[hi], self[lo]
swaps += 1
end
lo += 1
hi -= 1
end
if lo == hi && self[lo] > self[hi+1]
self[lo], self[hi+1] = self[hi+1], self[lo]
swaps += 1
end
swaps + _circle_sort!(low, mid) + _circle_sort!(mid+1, high)
end
end
 
ary = [6, 7, 8, 9, 2, 5, 3, 4, 1]
puts "before sort: #{ary}"
puts " after sort: #{ary.circle_sort!}"</lang>
 
{{out}}
<pre>
before sort: [6, 7, 8, 9, 2, 5, 3, 4, 1]
after sort: [1, 2, 3, 4, 5, 6, 7, 8, 9]
</pre>
 
=={{header|Sidef}}==
<lang ruby>func circlesort(arr, beg=0, end=arr.end) {
var swaps = 0
if (beg < end) {
var (lo, hi) = (beg, end)
do {
if (arr[lo] > arr[hi]) {
arr.swap(lo, hi)
++swaps
}
++hi if (--hi == ++lo)
} while (lo < hi)
swaps += circlesort(arr, beg, hi)
swaps += circlesort(arr, lo, end)
}
return swaps
}
 
var numbers = %n(2 3 3 5 5 1 1 7 7 6 6 4 4 0 0)
do { say numbers } while circlesort(numbers)
 
var strs = ["John", "Kate", "Zerg", "Alice", "Joe", "Jane", "Alice"]
do { say strs } while circlesort(strs)</lang>
{{out}}
<pre>
[2, 3, 3, 5, 5, 1, 1, 7, 7, 6, 6, 4, 4, 0, 0]
[0, 0, 1, 4, 1, 5, 3, 7, 2, 3, 4, 5, 6, 6, 7]
[0, 0, 1, 1, 2, 3, 3, 4, 4, 5, 5, 7, 6, 6, 7]
[0, 0, 1, 1, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7]
["John", "Kate", "Zerg", "Alice", "Joe", "Jane", "Alice"]
["Alice", "Jane", "Alice", "Joe", "John", "Kate", "Zerg"]
["Alice", "Alice", "Jane", "Joe", "John", "Kate", "Zerg"]
</pre>
 
=={{header|uBasic/4tH}}==
This one uses the optimized version featured at [http://sourceforge.net/p/forth-4th/wiki/Circle%20sort/ Sourceforge].
<lang>PRINT "Circle sort:"
n = FUNC (_InitArray)
Line 812 ⟶ 282:
END
 
_InnerCircle_Circle PARAM (23)
IF a@ = b@ THEN RETURN (c@)
LOCAL (3)
c@ = a@
d@ = b@
e@ = 0
 
LOCAL (3)
IF c@ = d@ THEN RETURN (0)
d@ = a@
e@ = b@
f@ = (b@-a@)/2
 
DO WHILE ca@ < db@
IF @(ca@) > @(db@) THEN PROC _Swap (c@, d@) : e@ = e@ + 1
c@ = c@ +PUSH 1@(a@)
d@ = d @(a@) -= 1@(b@)
@(b@) = POP()
c@ = c@ + 1
ENDIF
a@ = a@ + 1
b@ = b@ - 1
LOOP
 
IF a@ = b@ THEN
e@ = e@ + FUNC (_InnerCircle (a@, d@))
e@ = e@ + FUNCIF @(_InnerCircle (ca@,) > @(b@+1)) THEN
PUSH @(a@)
RETURN (e@)
@(a@) = @(b@+1)
@(b@+1) = POP()
c@ = c@ + 1
ENDIF
ENDIF
 
c@ = FUNC (_Circle (d@, d@+f@, c@))
c@ = FUNC (_Circle (d@+f@+1, e@, c@))
RETURN (c@)
 
 
_Circlesort PARAM(1) ' Circle sort
 
DO WHILE FUNC (_InnerCircle (0, a@-1))
DO WHILE FUNC (_Circle (0, a@-1, 0))
LOOP
RETURN
 
 
_Swap PARAM(2) ' Swap two array elements
PUSH @(a@)
@(a@) = @(b@)
@(b@) = POP()
RETURN
 
Line 861 ⟶ 340:
PRINT
RETURN</lang>
 
=={{header|zkl}}==
<lang zkl>fcn circleSort(list){
csort:=fcn(list,lo,hi,swaps){
if(lo==hi) return(swaps);
high,low,mid:=hi,lo,(hi-lo)/2;
while(lo<hi){
if(list[lo]>list[hi]){
list.swap(lo,hi);
swaps+=1;
}
lo+=1; hi-=1;
}
if(lo==hi)
if (list[lo]>list[hi+1]){
list.swap(lo,hi+1);
swaps+=1;
}
swaps=self.fcn(list,low,low + mid,swaps);
swaps=self.fcn(list,low + mid + 1,high,swaps);
return(swaps);
};
list.println();
while(csort(list,0,list.len()-1,0)){ list.println() }
list
}</lang>
<lang zkl>circleSort(L(6,7,8,9,2,5,3,4,1));
circleSort(L(5,-1,101,-4,0,1,8,6,2,3));</lang>
{{out}}
<pre>
L(6,7,8,9,2,5,3,4,1)
L(1,3,4,2,5,6,7,8,9)
L(1,2,3,4,5,6,7,8,9)
L(5,-1,101,-4,0,1,8,6,2,3)
L(-4,-1,0,3,6,1,2,8,5,101)
L(-4,-1,0,1,2,3,5,6,8,101)
</pre>
 
=={{header|ZX Spectrum Basic}}==
A language like ZX BASIC is not the most obvious choice for a routine which depends on local variables and recursion. This program proves that it can be implemented quite efficiently using arrays and global variables. The '''b''' and '''e''' variables are set up in such a way that they can be used for the first recursive call. The variables for the next recursion are saved in array '''s()''' which serves as a stack together with stack pointer '''p'''.
 
The size of the stack is determined by the amount of memory on the ZX Spectrum, which is 64KB (or 2<sup>16</sup> bytes). Each call requires two array elements. Note the size of a ZX Spectrum floating point number is 5 bytes, so this stack is slightly oversized. The somewhat strange indexing between both recursions is due to an stack pointer adjustment which was optimized away.
 
This version of Circle sort was based on the optimized version on [http://sourceforge.net/p/forth-4th/wiki/Circle%20sort/ Sourceforge]. It will also show a few asterisks while running, because it will take some time to finish (about two minutes).
 
<lang zxbasic>
10 DIM a(100): DIM s(32): RANDOMIZE : LET p=1: GO SUB 3000: GO SUB 2000: GO SUB 4000
20 STOP
1000 IF b=e THEN RETURN
1010 LET s(p)=b: LET s(p+1)=e
1020 IF a(s(p))>a(e) THEN LET t=a(s(p)): LET a(s(p))=a(e): LET a(e)=t: LET c=1
1030 LET s(p)=s(p)+1: LET e=e-1: IF s(p)<e THEN GO TO 1020
1040 LET p=p+2: GO SUB 1000: LET b=s(p-2): LET e=s(p-1): GO SUB 1000: LET p=p-2: RETURN
2000 PRINT "*";: LET b=1: LET e=100: LET c=0: GO SUB 1000: IF c>0 THEN GO TO 2000
2010 CLS : RETURN
3000 FOR x=1 TO 100: LET a(x)=RND: NEXT x: RETURN
4000 FOR x=1 TO 100: PRINT x,a(x): NEXT x: RETURN
</lang>
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