Update merge_sort.py

codes/python/chapter_sorting/merge_sort.py

@@ -41,7 +41,7 @@ def merge_sort(nums: list[int], left: int, right: int):
     if left >= right:
         return  # 当子数组长度为 1 时终止递归
     # 划分阶段
-    mid = left + (right - left) // 2  # 计算中点
+    mid = (left + right) // 2 # 计算中点
     merge_sort(nums, left, mid)  # 递归左子数组
     merge_sort(nums, mid + 1, right)  # 递归右子数组
     # 合并阶段