Merge Sort in Python 🧩

Stable and Efficient

Merge Sort is a Divide and Conquer algorithm. It divides the input array into two halves, calls itself for the two halves, and then merges the two sorted halves.

💻 Implementation

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(arr)

🎮 Interactive Merge Sort Demo

Speed:

ℹ️ Ready

Comparing/Active

Sorted

⚡ Time Complexity

Always O(n log n). It is very consistent but requires O(n) extra space.