Added Merge Sort algorithm in Python

Python/merge_sort.py

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+# merge_sort.py
+# Problem Statement: Implement the Merge Sort algorithm in Python.
+# Description: Merge Sort is a Divide and Conquer algorithm that divides the input array into two halves, 
+# recursively sorts them, and then merges the two sorted halves.
+# Complexity: 
+# - Time Complexity: O(n log n) for both average and worst-case scenarios.
+# - Space Complexity: O(n) due to the auxiliary space needed for merging.
+
+def merge_sort(arr):
+    # Base case: if the array has only one element, it's already sorted
+    if len(arr) > 1:
+        # Finding the mid-point of the array
+        mid = len(arr) // 2
+
+        # Dividing the array elements into two halves
+        left_half = arr[:mid]
+        right_half = arr[mid:]
+
+        # Recursively sort the two halves
+        merge_sort(left_half)
+        merge_sort(right_half)
+
+        i = j = k = 0
+
+        # Merging the sorted halves
+        while i < len(left_half) and j < len(right_half):
+            if left_half[i] < right_half[j]:
+                arr[k] = left_half[i]
+                i += 1
+            else:
+                arr[k] = right_half[j]
+                j += 1
+            k += 1
+
+        # Checking for remaining elements
+        while i < len(left_half):
+            arr[k] = left_half[i]
+            i += 1
+            k += 1
+
+        while j < len(right_half):
+            arr[k] = right_half[j]
+            j += 1
+            k += 1
+
+# Sample usage
+if __name__ == "__main__":
+    # Sample array to test the merge_sort function
+    array = [12, 11, 13, 5, 6, 7]
+    print("Original array:", array)
+    merge_sort(array)
+    print("Sorted array:", array)