OddEven Sort / Brick Sort (original) (raw)

Odd-Even Sort / Brick Sort

Last Updated : 23 Jul, 2025

This is basically a variation of bubble-sort. This algorithm is divided into two phases- Odd and Even Phase. The algorithm runs until the array elements are sorted and in each iteration two phases occurs- Odd and Even Phases.
In the odd phase, we perform a bubble sort on odd indexed elements and in the even phase, we perform a bubble sort on even indexed elements.

C++ `

// A C++ Program to implement Odd-Even / Brick Sort #include<bits/stdc++.h> using namespace std;

// A function to sort the algorithm using Odd Even sort void oddEvenSort(int arr[], int n) { bool isSorted = false; // Initially array is unsorted

while (!isSorted)
{
    isSorted = true;

    // Perform Bubble sort on odd indexed element
    for (int i=1; i<=n-2; i=i+2)
    {
        if (arr[i] > arr[i+1])
         {
            swap(arr[i], arr[i+1]);
            isSorted = false;
          }
    }

    // Perform Bubble sort on even indexed element
    for (int i=0; i<=n-2; i=i+2)
    {
        if (arr[i] > arr[i+1])
        {
            swap(arr[i], arr[i+1]);
            isSorted = false;
        }
    }
}

return;

}

// A utility function to print an array of size n void printArray(int arr[], int n) { for (int i=0; i < n; i++) cout << arr[i] << " "; cout << "\n"; }

// Driver program to test above functions. int main() { int arr[] = {34, 2, 10, -9}; int n = sizeof(arr)/sizeof(arr[0]);

oddEvenSort(arr, n);
printArray(arr, n);

return (0);

}

Java

// Java Program to implement // Odd-Even / Brick Sort import java.io.*;

class GFG { public static void oddEvenSort(int arr[], int n) { boolean isSorted = false; // Initially array is unsorted

    while (!isSorted)
    {
        isSorted = true;
        int temp =0;

        // Perform Bubble sort on odd indexed element
        for (int i=1; i<=n-2; i=i+2)
        {
            if (arr[i] > arr[i+1])
            {
                temp = arr[i];
                arr[i] = arr[i+1];
                arr[i+1] = temp;
                isSorted = false;
            }
        }

        // Perform Bubble sort on even indexed element
        for (int i=0; i<=n-2; i=i+2)
        {
            if (arr[i] > arr[i+1])
            {
                temp = arr[i];
                arr[i] = arr[i+1];
                arr[i+1] = temp;
                isSorted = false;
            }
        }
    }

    return;
}
public static void main (String[] args)
{
    int arr[] = {34, 2, 10, -9};
    int n = arr.length;

    oddEvenSort(arr, n);
    for (int i=0; i < n; i++)
        System.out.print(arr[i] + " ");

    System.out.println(" ");
}

} // Code Contributed by Mohit Gupta_OMG <(0_o)>

Python3

Python Program to implement

Odd-Even / Brick Sort

def oddEvenSort(arr, n): # Initially array is unsorted isSorted = 0 while isSorted == 0: isSorted = 1 temp = 0 for i in range(1, n-1, 2): if arr[i] > arr[i+1]: arr[i], arr[i+1] = arr[i+1], arr[i] isSorted = 0

    for i in range(0, n-1, 2):
        if arr[i] > arr[i+1]:
            arr[i], arr[i+1] = arr[i+1], arr[i]
            isSorted = 0

return

arr = [34, 2, 10, -9] n = len(arr)

oddEvenSort(arr, n); for i in range(0, n): print(arr[i], end = ' ')

Code Contributed by Mohit Gupta_OMG <(0_o)>

C#

// C# Program to implement // Odd-Even / Brick Sort using System;

class GFG { public static void oddEvenSort(int []arr, int n) { // Initially array is unsorted bool isSorted = false;

    while (!isSorted)
    {
        isSorted = true;
        int temp =0;

        // Perform Bubble sort on
        // odd indexed element
        for (int i = 1; i <= n - 2; i = i + 2)
        {
            if (arr[i] > arr[i+1])
            {
                temp = arr[i];
                arr[i] = arr[i+1];
                arr[i+1] = temp;
                isSorted = false;
            }
        }

        // Perform Bubble sort on
        // even indexed element
        for (int i = 0; i <= n - 2; i = i + 2)
        {
            if (arr[i] > arr[i+1])
            {
                temp = arr[i];
                arr[i] = arr[i+1];
                arr[i+1] = temp;
                isSorted = false;
            }
        }
    }
    return;
}

// Driver code
public static void Main ()
{
    int []arr = {34, 2, 10, -9};
    int n = arr.Length;
    
    // Function calling
    oddEvenSort(arr, n);
    for (int i = 0; i < n; i++)
        Console.Write(arr[i] + " ");

    Console.WriteLine(" ");
}

}

// This code is contributed by Sam007

JavaScript

`

Output :

-9 2 10 34

We demonstrate the above algorithm using the below illustration on the array = {3, 2, 3, 8, 5, 6, 4, 1}

Please refer wiki for proof of correctness.
Time Complexity : O(N2) where, N = Number of elements in the input array.
Auxiliary Space : O(1). Just like bubble sort this is also an in-place algorithm.
Exercise
In our program in each iteration we first do bubble sort on odd indexed elements and then a bubble sort on the even indexed elements.
Will we get a sorted result if we first perform a bubble sort on even indexed element first and then on the odd indexed element ?
References
https://en.wikipedia.org/wiki/Odd%E2%80%93even_sort