merge_sort.py

def merge_sort(arr):
    if len(arr) <= 1:
        return arr
    
    mid = len(arr) // 2
    left = arr[:mid]
    right = arr[mid:]
    
    left = merge_sort(left)
    right = merge_sort(right)
    
    return merge(left, right)

def merge(left, right):
    result = []
    i = 0
    j = 0
    while i < len(left) and j < len(right):
        if left[i] < right[j]:
            result.append(left[i])
            i += 1
        else:
            result.append(right[j])
            j += 1
            
    result += left[i:]
    result += right[j:]
    return result

# Example Usage
arr = [3, 6, 1, 9, 2, 8, 5, 7, 4]
sorted_arr = merge_sort(arr)
print("Original Array: ", arr)
print("Sorted Array: ", sorted_arr)