Selection sort

The idea of selection sort: iteratively find a smallest (or biggest) element in the remaining part of array and put it to the appropriate position.

The time complexity is pretty bad: O(n2).

This algorithm can only be used for fairly small arrays.

public class ImplementSelectionSort {

  private static void selectionSort(int[] array) {
    for (int i = 0; i < (array.length - 1); i++) {
      var smallestIndex = findSmallest(array, i);
      var buf = array[i];
      array[i] = array[smallestIndex];
      array[smallestIndex] = buf;
    }
  }

  public static int findSmallest(int[] array, int startingIndex) {
    var smallest = startingIndex;
    for (int i = startingIndex; i < array.length; i++) {
      if (array[i] < array[smallest]) {
        smallest = i;
      }
    }
    return smallest;
  }

  public static void main(String[] args) {
    var array = new int[]{22, 1, 3, 99, 8};
    selectionSort(array);
    for (var elem : array) {
      System.out.println(elem);
    }
  }
}

1 thought on “Selection sort”

  1. Pingback: Insertion sort – Mike Scherbakov

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