Simplify the declarations of the Python code.

codes/python/chapter_sorting/bubble_sort.py

@@ -7,7 +7,7 @@ Author: timi (xisunyy@163.com)
 
 def bubble_sort(nums: list[int]) -> None:
     """冒泡排序"""
-    n: int = len(nums)
+    n = len(nums)
     # 外循环：待排序元素数量为 n-1, n-2, ..., 1
     for i in range(n - 1, 0, -1):
         # 内循环：冒泡操作
@@ -19,10 +19,10 @@ def bubble_sort(nums: list[int]) -> None:
 
 def bubble_sort_with_flag(nums: list[int]) -> None:
     """冒泡排序（标志优化）"""
-    n: int = len(nums)
+    n = len(nums)
     # 外循环：待排序元素数量为 n-1, n-2, ..., 1
     for i in range(n - 1, 0, -1):
-        flag: bool = False  # 初始化标志位
+        flag = False  # 初始化标志位
         # 内循环：冒泡操作
         for j in range(i):
             if nums[j] > nums[j + 1]:
@@ -35,10 +35,10 @@ def bubble_sort_with_flag(nums: list[int]) -> None:
 
 """Driver Code"""
 if __name__ == "__main__":
-    nums: list[int] = [4, 1, 3, 1, 5, 2]
+    nums = [4, 1, 3, 1, 5, 2]
     bubble_sort(nums)
     print("排序后数组 nums =", nums)
 
-    nums1: list[int] = [4, 1, 3, 1, 5, 2]
+    nums1 = [4, 1, 3, 1, 5, 2]
     bubble_sort_with_flag(nums1)
     print("排序后数组 nums =", nums1)

codes/python/chapter_sorting/insertion_sort.py

@@ -9,8 +9,8 @@ def insertion_sort(nums: list[int]) -> None:
     """插入排序"""
     # 外循环：base = nums[1], nums[2], ..., nums[n-1]
     for i in range(1, len(nums)):
-        base: int = nums[i]
-        j: int = i - 1
+        base = nums[i]
+        j = i - 1
         # 内循环：将 base 插入到左边的正确位置
         while j >= 0 and nums[j] > base:
             nums[j + 1] = nums[j]  # 1. 将 nums[j] 向右移动一位
@@ -20,6 +20,6 @@ def insertion_sort(nums: list[int]) -> None:
 
 """Driver Code"""
 if __name__ == "__main__":
-    nums: list[int] = [4, 1, 3, 1, 5, 2]
+    nums = [4, 1, 3, 1, 5, 2]
     insertion_sort(nums)
     print("排序后数组 nums =", nums)

codes/python/chapter_sorting/merge_sort.py

@@ -10,16 +10,16 @@ def merge(nums: list[int], left: int, mid: int, right: int) -> None:
     # 左子数组区间 [left, mid]
     # 右子数组区间 [mid + 1, right]
     # 初始化辅助数组
-    tmp: list[int] = list(nums[left : right + 1])
+    tmp = list(nums[left : right + 1])
     # 左子数组的起始索引和结束索引
-    left_start: int = 0
-    left_end: int = mid - left
+    left_start = 0
+    left_end = mid - left
     # 右子数组的起始索引和结束索引
-    right_start: int = mid + 1 - left
-    right_end: int = right - left
+    right_start = mid + 1 - left
+    right_end = right - left
     # i, j 分别指向左子数组、右子数组的首元素
-    i: int = left_start
-    j: int = right_start
+    i = left_start
+    j = right_start
     # 通过覆盖原数组 nums 来合并左子数组和右子数组
     for k in range(left, right + 1):
         # 若“左子数组已全部合并完”，则选取右子数组元素，并且 j++
@@ -42,7 +42,7 @@ def merge_sort(nums: list[int], left: int, right: int) -> None:
     if left >= right:
         return  # 当子数组长度为 1 时终止递归
     # 划分阶段
-    mid: int = (left + right) // 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
@@ -51,6 +51,6 @@ def merge_sort(nums: list[int], left: int, right: int) -> None:
 
 """Driver Code"""
 if __name__ == "__main__":
-    nums: list[int] = [7, 3, 2, 6, 0, 1, 5, 4]
+    nums = [7, 3, 2, 6, 0, 1, 5, 4]
     merge_sort(nums, 0, len(nums) - 1)
     print("归并排序完成后 nums =", nums)

codes/python/chapter_sorting/quick_sort.py

@@ -29,7 +29,7 @@ class QuickSort:
         if left >= right:
             return
         # 哨兵划分
-        pivot: int = self.partition(nums, left, right)
+        pivot = self.partition(nums, left, right)
         # 递归左子数组、右子数组
         self.quick_sort(nums, left, pivot - 1)
         self.quick_sort(nums, pivot + 1, right)
@@ -51,7 +51,7 @@ class QuickSortMedian:
     def partition(self, nums: list[int], left: int, right: int) -> int:
         """哨兵划分（三数取中值）"""
         # 以 nums[left] 作为基准数
-        med: int = self.median_three(nums, left, (left + right) // 2, right)
+        med = self.median_three(nums, left, (left + right) // 2, right)
         # 将中位数交换至数组最左端
         nums[left], nums[med] = nums[med], nums[left]
         # 以 nums[left] 作为基准数
@@ -73,7 +73,7 @@ class QuickSortMedian:
         if left >= right:
             return
         # 哨兵划分
-        pivot: int = self.partition(nums, left, right)
+        pivot = self.partition(nums, left, right)
         # 递归左子数组、右子数组
         self.quick_sort(nums, left, pivot - 1)
         self.quick_sort(nums, pivot + 1, right)
@@ -102,7 +102,7 @@ class QuickSortTailCall:
         # 子数组长度为 1 时终止
         while left < right:
             # 哨兵划分操作
-            pivot: int = self.partition(nums, left, right)
+            pivot = self.partition(nums, left, right)
             # 对两个子数组中较短的那个执行快排
             if pivot - left < right - pivot:
                 self.quick_sort(nums, left, pivot - 1)  # 递归排序左子数组
@@ -115,16 +115,16 @@ class QuickSortTailCall:
 """Driver Code"""
 if __name__ == "__main__":
     # 快速排序
-    nums: list[int] = [2, 4, 1, 0, 3, 5]
+    nums = [2, 4, 1, 0, 3, 5]
     QuickSort().quick_sort(nums, 0, len(nums) - 1)
     print("快速排序完成后 nums =", nums)
 
     # 快速排序（中位基准数优化）
-    nums1: list[int] = [2, 4, 1, 0, 3, 5]
+    nums1 = [2, 4, 1, 0, 3, 5]
     QuickSortMedian().quick_sort(nums1, 0, len(nums1) - 1)
     print("快速排序（中位基准数优化）完成后 nums =", nums1)
 
     # 快速排序（尾递归优化）
-    nums2: list[int] = [2, 4, 1, 0, 3, 5]
+    nums2= [2, 4, 1, 0, 3, 5]
     QuickSortTailCall().quick_sort(nums2, 0, len(nums2) - 1)
     print("快速排序（尾递归优化）完成后 nums =", nums2)