# Selection sort

 Related content:

Selection sort is a sorting algorithm, a comparison sort that works as follows:

1. find the minimum value in the list
2. swap it with the value in the first position
3. sort the remainder of the list (excluding the first value)

It is probably the most intuitive sort algorithm to invent.

## Implementations

### C

```void selectionSort(int numbers[], int array_size)
{
int i, j;
int min, temp;

for (i = 0; i < array_size-1; i++)
{
min = i;
for (j = i+1; j < array_size; j++)
{
if (numbers[j] < numbers[min])
min = j;
}
temp = numbers[i];
numbers[i] = numbers[min];
numbers[min] = temp;
}
}
```

Original source: [1]

### Common Lisp

This is a recursive version. It doesn't really swap the values, it just creates a new list from the old one and returns that.

```(defun selection-sort (list)
(when list
(let ((minimum-element (reduce #'min list)))
(cons minimum-element
(selection-sort (remove minimum-element list))))))
```

### D

D version 1.x:

```import std.stdio: writefln;

void selectionSort(T)(T[] items) {
foreach(i, xi; items[0 .. \$-1]) {
int min = i;
for (int j = i+1; j < items.length; j++)
if (items[j] < items[min])
min = j;

items[i] = items[min];
items[min] = xi;
}
}

void main() {
auto a1 = "31415code9265codex358";
selectionSort(a1);
writefln(a1);

auto a2 = [3.2, 5.1, 0.0, -3.6, 11.1, 5.1];
selectionSort(a2);
writefln(a2);
}
```

The output:

```112334555689ccddeeoox
[-3.6,0,3.2,5.1,5.1,11.1]
```

### Erlang

```select_sort([]) -> [];
select_sort(List) -> select_sort(List, []).

select_sort([], Sorted) -> Sorted;
select_sort([H|T], Sorted) ->
{Max, Rest} = select_max(T, H, []),
select_sort(Rest, [Max|Sorted]).

select_max([], Max, Rest) -> {Max, Rest};
select_max([H|T], Max, Rest) when H < Max ->
select_max(T, Max, [H|Rest]);
select_max([H|T], Max, Rest) ->
select_max(T, H, [Max|Rest]).
```

### Java

``` public  void selectionSort(int data[],int n)
// pre: 0<=n <= data.length
// post: values in data[0..n-1] in ascending order
{
int numUnsorted=n; // number of values not in order
int index;       // general index
int max;
int temp;
while (numUnsorted > 0)
{
//determine a maximum value in Array
max=0;
for (index=1; index < numUnsorted; index++)
if (data[max] < data[index])
max=index;
// swap data[max] and data[numUnsorted-1]
temp                = data[max];
data[max]           = data[numUnsorted-1];
data[numUnsorted-1] = temp;
numUnsorted--;
}
}
```

### OCaml

The following function returns a pair of the smallest element in a list and the remaining list:

```# let rec select x = function
| [] -> x, []
| h::t ->
let x, h = if x<h then x, h else h, x in
let x, t = select x t in
x, h::t;;
val select : 'a -> 'a list -> 'a * 'a list = <fun>
```

The selection sort uses the "select" function to prepend each smallest element in turn:

```# let rec sort = function
| [] -> []
| h::t -> match select h t with
| h, t -> h::sort t;;
val sort : 'a list -> 'a list = <fun>
```

For example:

```# sort [1;6;2;7;3;8;4;9;5];;
- : int list = [1; 2; 3; 4; 5; 6; 7; 8; 9]
```

### Perl

```sub selectionSort {
my @list = @_;
for my \$i (0 .. \$#list - 1) {
my \$min = \$i;
for my \$j (\$i .. \$#list) {
if (\$list[\$j] < \$list[\$min]) {
\$min = \$j;
}
}
if (\$i != \$min) {
@list[\$i, \$min] = @list[\$min, \$i];
}
}
return @list;
}
my @unsorted = reverse(1 .. 10);
my @sorted = selectionSort(@unsorted);
```

### Python

```  def selection_sort(list):
l=list[:]                  # create a copy of the list
sorted=[]                  # this new list will hold the results
while len(l):              # while there are elements to sort...
lowest=l[0]            # create a variable to identify lowest
for x in l:            # and check every item in the list...
if x<lowest:       # to see if it might be lower.
lowest=x
sorted.append(lowest)  # add the lowest one to the new list
l.remove(lowest)       # and delete it from the old one
return sorted
```

### Ruby

```def selectionsort(list)
list.size.times do |start|
min = start
start.upto(list.size-1) do |i|
min = i if list[i] < list[min]
end
list[start], list[min] = list[min], list[start]
end
list
end
```

### 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) do
min := i;
for j range succ(i) 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;
```

Original source: [2]

### Turing

```var nombres, limit : int
get nombres
get limit
var last, smaller, bigger : int := 0
var rann, sort: array 1 .. nombres of int
for i : 1 .. nombres
rann (i) := Rand.Int (0, limit)
end for
for v : 1 .. upper (rann)
bigger := limit
for b : 1 .. upper (rann)
if rann (b) < bigger then
last := b
bigger := rann (b)
end if
end for
sort (v) := rann (last)
rann (last) := limit
end for
for b : 1 .. upper (sort)
put " ", sort (b) ..
end for
```