DevTut

# Bubble Sort

# Bubble Sort

The BubbleSort compares each successive pair of elements in an unordered list and inverts the elements if they are not in order.

The following example illustrates the bubble sort on the list {6,5,3,1,8,7,2,4} (pairs that were compared in each step are encapsulated in '**'):

{6,5,3,1,8,7,2,4}
{**5,6**,3,1,8,7,2,4} -- 5 < 6 -> swap
{5,**3,6**,1,8,7,2,4} -- 3 < 6 -> swap
{5,3,**1,6**,8,7,2,4} -- 1 < 6 -> swap
{5,3,1,**6,8**,7,2,4} -- 8 > 6 -> no swap
{5,3,1,6,**7,8**,2,4} -- 7 < 8 -> swap
{5,3,1,6,7,**2,8**,4} -- 2 < 8 -> swap
{5,3,1,6,7,2,**4,8**} -- 4 < 8 -> swap

After one iteration through the list, we have {5,3,1,6,7,2,4,8}. Note that the greatest unsorted value in the array (8 in this case) will always reach its final position. Thus, to be sure the list is sorted we must iterate n-1 times for lists of length n.

Graphic:

BubbleSort (opens new window)

# Implementation in C & C++

An example implementation of BubbleSort in C++:


  void bubbleSort(vector<int>numbers)
   {
       for(int i = numbers.size() - 1; i >= 0; i--) {
           for(int j = 1; j <= i; j++) {
               if(numbers[j-1] > numbers[j]) {
                   swap(numbers[j-1],numbers(j));
               }
           }
       }
   }

C Implementation

void bubble_sort(long list[], long n)
{
  long c, d, t;
 
  for (c = 0 ; c < ( n - 1 ); c++)
  {
    for (d = 0 ; d < n - c - 1; d++)
    {
      if (list[d] > list[d+1])
      {
        /* Swapping */
 
        t         = list[d];
        list[d]   = list[d+1];
        list[d+1] = t;
      }
    }
  }
}

Bubble Sort with pointer

void pointer_bubble_sort(long * list, long n)
{
  long c, d, t;
 
  for (c = 0 ; c < ( n - 1 ); c++)
  {
    for (d = 0 ; d < n - c - 1; d++)
    {
      if ( * (list + d ) > *(list+d+1))
      {
        /* Swapping */
 
        t         = * (list + d );
        * (list + d )   = * (list + d + 1 );
        * (list + d + 1) = t;
      }
    }
  }
}

# Implementation in Javascript

function bubbleSort(a)
    {
        var swapped;
        do {
            swapped = false;
            for (var i=0; i < a.length-1; i++) {
                if (a[i] > a[i+1]) {
                    var temp = a[i];
                    a[i] = a[i+1];
                    a[i+1] = temp;
                    swapped = true;
                }
            }
        } while (swapped);
    }

var a = [3, 203, 34, 746, 200, 984, 198, 764, 9];
bubbleSort(a);
console.log(a); //logs [ 3, 9, 34, 198, 200, 203, 746, 764, 984 ]

# Implementation in C#

Bubble sort is also known as Sinking Sort. It is a simple sorting algorithm that repeatedly steps through the list to be sorted, compares each pair of adjacent items and swaps them if they are in the wrong order.

Bubble sort example Bubble sort example (opens new window)

Implementation of Bubble Sort
I used C# language to implement bubble sort algorithm

public class BubbleSort
{
    public static void SortBubble(int[] input)
    {
        for (var i = input.Length - 1; i >= 0; i--)
        {
            for (var j = input.Length - 1 - 1; j >= 0; j--)
            {
                if (input[j] <= input[j + 1]) continue;
                var temp = input[j + 1];
                input[j + 1] = input[j];
                input[j] = temp;
            }
        }
    }

    public static int[] Main(int[] input)
    {
        SortBubble(input);
        return input;
    }
}

# Implementation in Java

public class MyBubbleSort {
  
    public static void bubble_srt(int array[]) {//main logic
        int n = array.length;
        int k;
        for (int m = n; m >= 0; m--) {
            for (int i = 0; i < n - 1; i++) {
                k = i + 1;
                if (array[i] > array[k]) {
                    swapNumbers(i, k, array);
                }
            }
            printNumbers(array);
        }
    }
  
    private static void swapNumbers(int i, int j, int[] array) {
  
        int temp;
        temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
  
    private static void printNumbers(int[] input) {
          
        for (int i = 0; i < input.length; i++) {
            System.out.print(input[i] + ", ");
        }
        System.out.println("\n");
    }
  
    public static void main(String[] args) {
        int[] input = { 4, 2, 9, 6, 23, 12, 34, 0, 1 };
        bubble_srt(input);
  
    }
}

# Python Implementation

#!/usr/bin/python

input_list = [10,1,2,11]

for i in range(len(input_list)):
  for j in range(i):
    if int(input_list[j]) > int(input_list[j+1]):
      input_list[j],input_list[j+1] = input_list[j+1],input_list[j]

print input_list

# Parameters

Parameter Description
Stable Yes
In place Yes
Best case complexity O(n)
Average case complexity O(n^2)
Worst case complexity O(n^2)
Space complexity O(1)

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