Python Program for Odd-Even Sort / Brick Sort

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. 

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 Contribute by Mohit Gupta_OMG <(0_o)>

Output

-9 2 10 34 

Time Complexity: O(n²)
Auxiliary Space: O(1)

Python Program for Odd-Even Sort / Brick Sort Using the sorted() function 

In this method, the sorted() function is used to sort odd-indexed and even-indexed elements of the array separately, and then assign them back to the original array using slicing. 

This replaces the first for loop in the original code. The rest of the code remains the same.

Below is the code for the above approach: 

Python3

def oddEvenSort(arr, n):
    isSorted = 0
    while isSorted == 0:
        isSorted = 1
        arr[1::2], arr[2::2] = sorted(arr[1::2]), sorted(arr[2::2])

        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 =" ")

Output

-9 10 2 34 

Time Complexity: O(n²)
Auxiliary Space: O(1)

Please refer complete article on Odd-Even Sort / Brick Sort for more details!