bubble_sort.java

// Implementation of Bubble sort.
// Bubble sort, sometimes referred to as sinking sort, is a simple sorting algorithm
// that repeatedly steps through the input list element by element,
// comparing the current element with the one after it, swapping their values if needed.
//  These passes through the list are repeated until no swaps had to be performed during a pass,
// meaning that the list has become fully sorted. (Source wiki) https://en.wikipedia.org/wiki/Bubble_sort

// Time Complexity worst-case and average complexity O(n^{2})
// Bubble sort is O(n) on a list that is already sorted i.e. Best case

// Sample Input : [2, 1, 9, 3, 5, 4, 0]
// Output : [0 1 2 3 4 5 9]


public class BubbleSort {
    public static void bubbleSort(int[] arr) {
        int n = arr.length;
        // Traverse through all array elements
        for (int i = 0; i < n - 1; i++) {
            // Last i elements are already in place
            for (int j = 0; j < n - i - 1; j++) {
                // Swap adjacent elements if they are in the wrong order
                if (arr[j] > arr[j + 1]) {
                    int temp = arr[j];
                    arr[j] = arr[j + 1];
                    arr[j + 1] = temp;
                }
            }
        }
    }

    public static void main(String[] args) {
        int[] arr = {64, 34, 25, 12, 22, 11, 90};
        bubbleSort(arr);
        System.out.println("Sorted array: ");
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}