merge

Author: Pragati Gupta

Python/algorithms/sorting/merge_sort.py

@@ -1,26 +1,65 @@
+# 📌 Merge Sort Algorithm
+# Language: Python
+# Category: Sorting
+# Time Complexity: O(n log n)
+# Space Complexity: O(n)
+
+"""
+Merge Sort is a classic Divide and Conquer algorithm.
+It works in three main steps:
+1. Divide: Split the array into two halves.
+2. Conquer: Recursively sort the two halves.
+3. Combine: Merge the two sorted halves into a single sorted array.
+"""
+
 def merge_sort(arr):
+    """
+    Sorts the input list 'arr' using the Merge Sort algorithm.
+    :param arr: list of elements (int/float) to be sorted
+    :return: sorted list
+    """
+    # Base condition: if array has 0 or 1 elements, it's already sorted
     if len(arr) <= 1:
         return arr
+
+    # Step 1: Divide the array into two halves
     mid = len(arr) // 2
     left_half = merge_sort(arr[:mid])
     right_half = merge_sort(arr[mid:])
+
+    # Step 2: Merge the sorted halves
     return merge(left_half, right_half)
 
+
 def merge(left, right):
+    """
+    Merges two sorted lists 'left' and 'right' into a single sorted list.
+    :param left: sorted list
+    :param right: sorted list
+    :return: merged sorted list
+    """
     merged = []
     i = j = 0
+
+    # Compare elements of both halves and add the smaller one
     while i < len(left) and j < len(right):
         if left[i] <= right[j]:
             merged.append(left[i])
             i += 1
         else:
             merged.append(right[j])
             j += 1
+
+    # If there are remaining elements in left or right, add them
     merged.extend(left[i:])
     merged.extend(right[j:])
+
     return merged
 
+
+# 🧪 Example usage
 if __name__ == "__main__":
-    arr = list(map(int, input("Enter numbers separated by space: ").split()))
-    sorted_arr = merge_sort(arr)
-    print("Sorted array:", sorted_arr)
+    sample_array = [38, 27, 43, 3, 9, 82, 10]
+    print("Original array:", sample_array)
+    sorted_array = merge_sort(sample_array)
+    print("Sorted array:", sorted_array)