Understanding the Merge Sort Algorithm

Introduction

This tutorial will guide you through understanding the merge sort algorithm and how to implement it in Python.

Step 1: Define the Problem

We are given an array of numbers and we need to sort it in ascending order.

Step 2: Divide the Array

We will divide the array into two halves until we have subarrays of size 1.

Step 3: Merge the Subarrays

We will merge the subarrays in a way that the resulting array is sorted.

Step 4: Repeat the Process

We will repeat the process until the entire array is sorted.

Example Code

def merge_sort(array):
    if len(array) <= 1:
        return array
    mid = len(array) // 2
    left_half = array[:mid]
    right_half = array[mid:]
    return merge(merge_sort(left_half), merge_sort(right_half))
def merge(left, right):
    merged = []
    left_index = 0
    right_index = 0
    while left_index < len(left) and right_index < len(right):
        if left[left_index] <= right[right_index] :
            merged.append(left[left_index])
            left_index += 1
        else:
            merged.append(right[right_index])
            right_index += 1
    merged += left[left_index:]
    merged += right[right_index:]
    return merged
print(merge_sort([64, 34, 25, 12, 22, 11, 90]))  # Output: [11, 12, 22, 25, 34, 64, 90]

Conclusion

In this tutorial, we learned how the merge sort algorithm works and how to implement it in Python.