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# Selection Sort

• Difficulty Level : Easy
• Last Updated : 28 Jun, 2021

The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from unsorted part and putting it at the beginning. The algorithm maintains two subarrays in a given array.
1) The subarray which is already sorted.
2) Remaining subarray which is unsorted.
In every iteration of selection sort, the minimum element (considering ascending order) from the unsorted subarray is picked and moved to the sorted subarray.
Following example explains the above steps:

```arr[] = 64 25 12 22 11

// Find the minimum element in arr[0...4]
// and place it at beginning
11 25 12 22 64

// Find the minimum element in arr[1...4]
// and place it at beginning of arr[1...4]
11 12 25 22 64

// Find the minimum element in arr[2...4]
// and place it at beginning of arr[2...4]
11 12 22 25 64

// Find the minimum element in arr[3...4]
// and place it at beginning of arr[3...4]
11 12 22 25 64 ```

Flowchart of the Selection Sort: ## C++

 `// C++ program for implementation of selection sort``#include ``using` `namespace` `std;` `void` `swap(``int` `*xp, ``int` `*yp)``{``    ``int` `temp = *xp;``    ``*xp = *yp;``    ``*yp = temp;``}` `void` `selectionSort(``int` `arr[], ``int` `n)``{``    ``int` `i, j, min_idx;` `    ``// One by one move boundary of unsorted subarray``    ``for` `(i = 0; i < n-1; i++)``    ``{``        ``// Find the minimum element in unsorted array``        ``min_idx = i;``        ``for` `(j = i+1; j < n; j++)``        ``if` `(arr[j] < arr[min_idx])``            ``min_idx = j;` `        ``// Swap the found minimum element with the first element``        ``swap(&arr[min_idx], &arr[i]);``    ``}``}` `/* Function to print an array */``void` `printArray(``int` `arr[], ``int` `size)``{``    ``int` `i;``    ``for` `(i=0; i < size; i++)``        ``cout << arr[i] << ``" "``;``    ``cout << endl;``}` `// Driver program to test above functions``int` `main()``{``    ``int` `arr[] = {64, 25, 12, 22, 11};``    ``int` `n = ``sizeof``(arr)/``sizeof``(arr);``    ``selectionSort(arr, n);``    ``cout << ``"Sorted array: \n"``;``    ``printArray(arr, n);``    ``return` `0;``}` `// This is code is contributed by rathbhupendra`

## C

 `// C program for implementation of selection sort``#include ` `void` `swap(``int` `*xp, ``int` `*yp)``{``    ``int` `temp = *xp;``    ``*xp = *yp;``    ``*yp = temp;``}` `void` `selectionSort(``int` `arr[], ``int` `n)``{``    ``int` `i, j, min_idx;` `    ``// One by one move boundary of unsorted subarray``    ``for` `(i = 0; i < n-1; i++)``    ``{``        ``// Find the minimum element in unsorted array``        ``min_idx = i;``        ``for` `(j = i+1; j < n; j++)``          ``if` `(arr[j] < arr[min_idx])``            ``min_idx = j;` `        ``// Swap the found minimum element with the first element``        ``swap(&arr[min_idx], &arr[i]);``    ``}``}` `/* Function to print an array */``void` `printArray(``int` `arr[], ``int` `size)``{``    ``int` `i;``    ``for` `(i=0; i < size; i++)``        ``printf``(``"%d "``, arr[i]);``    ``printf``(``"\n"``);``}` `// Driver program to test above functions``int` `main()``{``    ``int` `arr[] = {64, 25, 12, 22, 11};``    ``int` `n = ``sizeof``(arr)/``sizeof``(arr);``    ``selectionSort(arr, n);``    ``printf``(``"Sorted array: \n"``);``    ``printArray(arr, n);``    ``return` `0;``}`

## Python

 `# Python program for implementation of Selection``# Sort``import` `sys``A ``=` `[``64``, ``25``, ``12``, ``22``, ``11``]` `# Traverse through all array elements``for` `i ``in` `range``(``len``(A)):``    ` `    ``# Find the minimum element in remaining``    ``# unsorted array``    ``min_idx ``=` `i``    ``for` `j ``in` `range``(i``+``1``, ``len``(A)):``        ``if` `A[min_idx] > A[j]:``            ``min_idx ``=` `j``            ` `    ``# Swap the found minimum element with``    ``# the first element       ``    ``A[i], A[min_idx] ``=` `A[min_idx], A[i]` `# Driver code to test above``print` `(``"Sorted array"``)``for` `i ``in` `range``(``len``(A)):``    ``print``(``"%d"` `%``A[i]),`

## Java

 `// Java program for implementation of Selection Sort``class` `SelectionSort``{``    ``void` `sort(``int` `arr[])``    ``{``        ``int` `n = arr.length;` `        ``// One by one move boundary of unsorted subarray``        ``for` `(``int` `i = ``0``; i < n-``1``; i++)``        ``{``            ``// Find the minimum element in unsorted array``            ``int` `min_idx = i;``            ``for` `(``int` `j = i+``1``; j < n; j++)``                ``if` `(arr[j] < arr[min_idx])``                    ``min_idx = j;` `            ``// Swap the found minimum element with the first``            ``// element``            ``int` `temp = arr[min_idx];``            ``arr[min_idx] = arr[i];``            ``arr[i] = temp;``        ``}``    ``}` `    ``// Prints the array``    ``void` `printArray(``int` `arr[])``    ``{``        ``int` `n = arr.length;``        ``for` `(``int` `i=``0``; i

## C#

 `// C# program for implementation``// of Selection Sort``using` `System;` `class` `GFG``{``    ``static` `void` `sort(``int` `[]arr)``    ``{``        ``int` `n = arr.Length;` `        ``// One by one move boundary of unsorted subarray``        ``for` `(``int` `i = 0; i < n - 1; i++)``        ``{``            ``// Find the minimum element in unsorted array``            ``int` `min_idx = i;``            ``for` `(``int` `j = i + 1; j < n; j++)``                ``if` `(arr[j] < arr[min_idx])``                    ``min_idx = j;` `            ``// Swap the found minimum element with the first``            ``// element``            ``int` `temp = arr[min_idx];``            ``arr[min_idx] = arr[i];``            ``arr[i] = temp;``        ``}``    ``}` `    ``// Prints the array``    ``static` `void` `printArray(``int` `[]arr)``    ``{``        ``int` `n = arr.Length;``        ``for` `(``int` `i=0; i

## PHP

 ` ``\$arr``[``\$low``])``        ``{``            ``\$tmp` `= ``\$arr``[``\$i``];``            ``\$arr``[``\$i``] = ``\$arr``[``\$low``];``            ``\$arr``[``\$low``] = ``\$tmp``;``        ``}``    ``}``}` `// Driver Code``\$arr` `= ``array``(64, 25, 12, 22, 11);``\$len` `= ``count``(``\$arr``);``selection_sort(``\$arr``, ``\$len``);``echo` `"Sorted array : \n"``;` `for` `(``\$i` `= 0; ``\$i` `< ``\$len``; ``\$i``++)``    ``echo` `\$arr``[``\$i``] . ``" "``;` `// This code is contributed``// by Deepika Gupta.``?>`

## Javascript

 ``
Output:
```Sorted array:
11 12 22 25 64```

Time Complexity: O(n2) as there are two nested loops.
Auxiliary Space: O(1)
The good thing about selection sort is it never makes more than O(n) swaps and can be useful when memory write is a costly operation.
Exercise :
Sort an array of strings using Selection Sort
Stability : The default implementation is not stable. However it can be made stable. Please see stable selection sort for details.
In Place : Yes, it does not require extra space.

Snapshots:
Quiz on Selection Sort
Other Sorting Algorithms on GeeksforGeeks/GeeksQuiz:

Coding practice for sorting.