Open In App
Related Articles

Bubble sort using two Stacks

Improve
Improve
Improve
Like Article
Like
Save Article
Save
Report issue
Report

Prerequisite : Bubble Sort 
Write a function that sort an array of integers using stacks and also uses bubble sort paradigm.

Algorithm:  

1. Push all elements of array in 1st stack

2. Run a loop for 'n' times(n is size of array)
   having the following :
   2.a. Keep on pushing elements in the 2nd 
        stack till the top of second stack is 
        smaller than element being pushed from 
        1st stack.
   2.b. If the element being pushed is smaller 
        than top of 2nd stack then swap them
        (as in bubble sort)
   *Do above steps alternatively

TRICKY STEP: Once a stack is empty, then the 
top of the next stack will be the largest 
number so keep it at its position in array 
i.e arr[len-1-i] and then pop it from that 
stack.

Implementation:

C++

// C++ program for bubble sort
// using stack
#include <bits/stdc++.h>
using namespace std;
 
// Function for bubble sort using Stack
void bubbleSortStack(int a[], int n)
{
    stack<int> s1;
     
    // Push all elements of array in 1st stack
    for(int i = 0; i < n; i++)
    {
        s1.push(a[i]);
    }
 
    stack<int> s2;
 
    for(int i = 0; i < n; i++)
    {
        if (i % 2 == 0)
        {
            while (!s1.empty())
            {
                int t = s1.top();
                s1.pop();
 
                if (s2.empty())
                {
                    s2.push(t);
                }
 
                else
                {
                    // Swapping
                    if (s2.top() > t)
                    {
                        int temp = s2.top();
                        s2.pop();
                        s2.push(t);
                        s2.push(temp);
                    }
                    else
                    {
                        s2.push(t);
                    }
                }
            }
             
            // Tricky step
            a[n - 1 - i] = s2.top();
            s2.pop();
        }
 
        else
        {
            while (!s2.empty())
            {
                int t = s2.top();
                s2.pop();
 
                if (s1.empty())
                {
                    s1.push(t);
                }
 
                else
                {
                    if (s1.top() > t)
                    {
                        int temp = s1.top();
                        s1.pop();
 
                        s1.push(t);
                        s1.push(temp);
                    }
 
                    else
                    {
                        s1.push(t);
                    }
                }
            }
             
            // Tricky step
            a[n - 1 - i] = s1.top();
            s1.pop();
        }
    }
     
    cout << "[";
    for(int i = 0; i < n; i++)
    {
        cout << a[i] << ", ";
    }
    cout << "]";
}
 
// Driver code
int main()
{
    int a[] = { 15, 12, 44, 2, 5, 10 };
    int n = sizeof(a) / sizeof(a[0]);
 
    bubbleSortStack(a, n);
 
    return 0;
}
 
// This code is contributed by pawki

                    

Java

// Java program for bubble sort
// using stack
 
import java.util.Arrays;
import java.util.Stack;
 
public class Test
{
    // Method for bubble sort using Stack
    static void bubbleSortStack(int arr[], int n)
    {
        Stack<Integer> s1 = new Stack<>();
         
        // Push all elements of array in 1st stack
        for (int num : arr)
            s1.push(num);    
         
        Stack<Integer> s2 = new Stack<>();
         
        for (int i = 0; i < n; i++)
        {
            // alternatively
            if (i % 2 == 0)
            {
                while (!s1.isEmpty())
                {
                    int t = s1.pop();
                     
                    if (s2.isEmpty())
                        s2.push(t);                    
                    else
                    {
                        if (s2.peek() > t)
                        {
                            // swapping
                            int temp = s2.pop();
                            s2.push(t);
                            s2.push(temp);
                        }
                        else
                        {
                            s2.push(t);
                        }
                    }
                }
                 
                // tricky step
                arr[n-1-i] = s2.pop();
            }            
            else
            {
                while(!s2.isEmpty())
                {
                    int t = s2.pop();
                     
                    if (s1.isEmpty())
                        s1.push(t);
                     
                    else
                    {
                        if (s1.peek() > t)
                        {
                            // swapping
                            int temp = s1.pop();
                             
                            s1.push(t);
                            s1.push(temp);
                        }
                        else
                            s1.push(t);
                    }
                }
                 
                // tricky step
                arr[n-1-i] = s1.pop();
            }
        }        
        System.out.println(Arrays.toString(arr));
    }
     
    // Driver Method
    public static void main(String[] args)
    {
        int arr[] = {15, 12, 44, 2, 5, 10};    
        bubbleSortStack(arr, arr.length);
    }
}

                    

Python3

# Python3 program for bubble sort
# using stack
 
# Function for bubble sort using Stack
def bubbleSortStack(a, n):
    s1 = []
     
    # Push all elements of array in 1st stack
    for i in range(n):
        s1.append(a[i]);
    s2 = []
    for i in range(n):
        if (i % 2 == 0):
            while (len(s1) != 0):
                t = s1[-1]
                s1.pop();
                if(len(s2) == 0):
                    s2.append(t);                  
                else:
                 
                    # Swapping
                    if (s2[-1] > t):
                        temp = s2[-1]
                        s2.pop();
                        s2.append(t);
                        s2.append(temp);
                     
                    else:
                        s2.append(t);
                     
            # Tricky step
            a[n - 1 - i] = s2[-1]
            s2.pop();          
        else:
         
            while(len(s2) != 0):
                t = s2[-1]
                s2.pop();
 
                if(len(s1) == 0):
                    s1.append(t);
                else:
                    if (s1[-1] > t):
                        temp = s1[-1]
                        s1.pop();
 
                        s1.append(t);
                        s1.append(temp);
                    else:
                        s1.append(t);
                     
            # Tricky step
            a[n - 1 - i] = s1[-1]
            s1.pop();
    print("[", end = '')
    for i in range(n):
        print(a[i], end = ', ')
    print(']', end = '')
 
# Driver code
if __name__=='__main__':
     
    a = [ 15, 12, 44, 2, 5, 10 ]
    n = len(a)
 
    bubbleSortStack(a, n);
     
    # This code is contributed by rutvik_56.

                    

C#

// C# program for bubble sort
// using stack
using System;
using System.Collections.Generic;
 
class GFG
{
     
// Method for bubble sort using Stack
static void bubbleSortStack(int []arr, int n)
{
    Stack<int> s1 = new Stack<int>();
     
    // Push all elements of array in 1st stack
    foreach (int num in arr)
        s1.Push(num);    
     
    Stack<int> s2 = new Stack<int>();
     
    for (int i = 0; i < n; i++)
    {
        // alternatively
        if (i % 2 == 0)
        {
            while (s1.Count != 0)
            {
                int t = s1.Pop();
                 
                if (s2.Count == 0)
                    s2.Push(t);                
                else
                {
                    if (s2.Peek() > t)
                    {
                        // swapping
                        int temp = s2.Pop();
                        s2.Push(t);
                        s2.Push(temp);
                    }
                    else
                    {
                        s2.Push(t);
                    }
                }
            }
             
            // tricky step
            arr[n - 1 - i] = s2.Pop();
        }        
        else
        {
            while(s2.Count != 0)
            {
                int t = s2.Pop();
                 
                if (s1.Count == 0)
                    s1.Push(t);
                 
                else
                {
                    if (s1.Peek() > t)
                    {
                        // swapping
                        int temp = s1.Pop();
                         
                        s1.Push(t);
                        s1.Push(temp);
                    }
                    else
                        s1.Push(t);
                }
            }
             
            // tricky step
            arr[n - 1 - i] = s1.Pop();
        }
    }    
    Console.WriteLine("[" + String.Join(", ", arr) + "]");
}
 
// Driver Code
public static void Main(String[] args)
{
    int []arr = {15, 12, 44, 2, 5, 10};    
    bubbleSortStack(arr, arr.Length);
}
}
 
// This code is contributed by 29AjayKumar

                    

Javascript

<script>
 
// Javascript program for bubble sort
// using stack
 
// Method for bubble sort using Stack
function bubbleSortStack(arr, n)
{
    let s1 = [];
          
    // Push all elements of array in 1st stack
    for(let num = 0; num < arr.length; num++)
        s1.push(arr[num]);   
      
    let s2 = [];
      
    for(let i = 0; i < n; i++)
    {
         
        // Alternatively
        if (i % 2 == 0)
        {
            while (s1.length != 0)
            {
                let t = s1.pop();
                  
                if (s2.length == 0)
                    s2.push(t);                   
                else
                {
                    if (s2[s2.length - 1] > t)
                    {
                         
                        // Swapping
                        let temp = s2.pop();
                        s2.push(t);
                        s2.push(temp);
                    }
                    else
                    {
                        s2.push(t);
                    }
                }
            }
              
            // Tricky step
            arr[n - 1 - i] = s2.pop();
        }           
        else
        {
            while(s2.length != 0)
            {
                let t = s2.pop();
                  
                if (s1.length == 0)
                    s1.push(t);
                  
                else
                {
                    if (s1[s1.length - 1] > t)
                    {
                         
                        // Swapping
                        let temp = s1.pop();
                          
                        s1.push(t);
                        s1.push(temp);
                    }
                    else
                        s1.push(t);
                }
            }
              
            // Tricky step
            arr[n - 1 - i] = s1.pop();
        }
    }       
    document.write((arr).join(" "));
}
 
// Driver code
let arr = [ 15, 12, 44, 2, 5, 10 ];
bubbleSortStack(arr, arr.length);
 
// This code is contributed by rag2127
 
</script>

                    

Output
[2, 5, 10, 12, 15, 44, ]

Time Complexity: O(n2) // we are using a for loop from 0 to n-1 and inside it we are traversing the stack elements hence the complexity is quadratic
Auxiliary Space: O(n) // since we are using a stack to store all the elements hence takes up the space

 



Last Updated : 14 Feb, 2023
Like Article
Save Article
Share your thoughts in the comments
Similar Reads