In this tutorial, we will discuss a Python program for merge sort algorithm to sort an array of numbers in ascending order.

Before going to the program first, let us understand what is Merge Sort.

Merge Sort:

• Merge sort is a divide-and-conquer sorting algorithm that divides the array into two halves, sorts each half, and then merges them back together.

Related: Python program for Quick Sort

Program code for Merge Sort in Python

# Merge Sort in Python
def merge_sort(arr):
    if len(arr) > 1:
        mid = len(arr) // 2
        L = arr[:mid]
        R = arr[mid:]

        merge_sort(L)
        merge_sort(R)

        i = j = k = 0

        while i < len(L) and j < len(R):
            if L[i] < R[j]:
                arr[k] = L[i]
                i += 1
            else:
                arr[k] = R[j]
                j += 1
            k += 1

        while i < len(L):
            arr[k] = L[i]
            i += 1
            k += 1

        while j < len(R):
            arr[k] = R[j]
            j += 1
            k += 1

arr = [12, 11, 13, 5, 6, 7]
merge_sort(arr)
print("Sorted array:", arr)

Explanation

1. Function Definition: The merge_sort function takes an array arr as input and sorts it in ascending order using the merge sort algorithm.
2. Main Program: The program defines an unsorted array and sorts it using the merge_sort function. It then prints the sorted array.

Output

• When you run the above program, it will sort the array using merge sort and print the sorted result.

Conclusion

• In this tutorial, we learned how to implement the merge sort algorithm in Python.
• Understanding this concept is essential for solving various sorting problems and enhancing your programming skills.