Selection Sort

Find the minimum element in the sequence and swap it with the element at the current position. Repeat this process for all elements until the entire sequence is sorted.

1. First, find the minimum (or maximum) element in the unsorted sequence and store it at the beginning of the sorted sequence.
2. Continue to find the minimum (or maximum) element from the remaining unsorted elements and place it at the end of the sorted sequence.
3. Repeat step 2 until all elements are sorted.

Code Implementation

::: code-tabs
@tab Java

public class SelectionSort implements IArraySort {
    @Override
    public int[] sort(int[] sourceArray) throws Exception {
        int[] arr = Arrays.copyOf(sourceArray, sourceArray.length);
        // Total of N-1 comparison rounds required
        for (int i = 0; i < arr.length - 1; i++) {
            int min = i;
            // Number of comparisons per round: N-i
            for (int j = i + 1; j < arr.length; j++) {
                if (arr[j] < arr[min]) {
                    // Record the index of the minimum element found so far
                    min = j;
                }
            }
            // Swap the found minimum element with the element at position i
            if (i != min) {
                int tmp = arr[i];
                arr[i] = arr[min];
                arr[min] = tmp;
            }
        }
        return arr;
    }
}

@tab JavaScript

function selectionSort(arr) {
    var len = arr.length;
    var minIndex, temp;
    for (var i = 0; i < len - 1; i++) {
        minIndex = i;
        for (var j = i + 1; j < len; j++) {
            if (arr[j] < arr[minIndex]) {     // Find the smallest number
                minIndex = j;                 // Save the index of the smallest number
            }
        }
        temp = arr[i];
        arr[i] = arr[minIndex];
        arr[minIndex] = temp;
    }
    return arr;
}

@tab Python

def selectionSort(arr):
    for i in range(len(arr) - 1):
        # Record the index of the smallest number
        minIndex = i
        for j in range(i + 1, len(arr)):
            if arr[j] < arr[minIndex]:
                minIndex = j
        # If i is not the smallest number, swap i with the smallest number
        if i != minIndex:
            arr[i], arr[minIndex] = arr[minIndex], arr[i]
    return arr

@tab Go

func selectionSort(arr []int) []int {
    length := len(arr)
    for i := 0; i < length-1; i++ {
        min := i
        for j := i + 1; j < length; j++ {
            if arr[min] > arr[j] {
                min = j
            }
        }
        arr[i], arr[min] = arr[min], arr[i]
    }
    return arr
}

@tab PHP

function selectionSort($arr){
    $len = count($arr);
    for ($i = 0; $i < $len - 1; $i++) {
        $minIndex = $i;
        for ($j = $i + 1; $j < $len; $j++) {
            if ($arr[$j] < $arr[$minIndex]) {
                $minIndex = $j;
            }
        }
        $temp = $arr[$i];
        $arr[$i] = $arr[$minIndex];
        $arr[$minIndex] = $temp;
    }
    return $arr;
}

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