Update problems/53.maximum-sum-subarray-cn.en.md, python code reforma…

problems/53.maximum-sum-subarray-cn.en.md

@@ -151,18 +151,21 @@ _Python3 code_ `(TLE)`
 
 ```python
 import sys
+
 class Solution:
-def maxSubArray(self, nums: List[int]) -> int:
-n = len(nums)
-maxSum = -sys. maxsize
-sum = 0
-for i in range(n):
-sum = 0
-for j in range(i, n):
-sum += nums[j]
-maxSum = max(maxSum, sum)
-
-return maxSum
+    def maxSubArray(self, nums: list[int]) -> int:
+        n = len(nums)
+        maxSum = -sys. maxsize
+        sum = 0
+
+        for i in range(n):
+            sum = 0
+
+            for j in range(i, n):
+                sum += nums[j]
+                maxSum = max(maxSum, sum)
+
+        return maxSum
 ```
 
 _Javascript code_ from [**@lucifer**](https://github.com/azl397985856)
@@ -213,16 +216,16 @@ _Python3 code_
 
 ```python
 class Solution:
-def maxSubArray(self, nums: List[int]) -> int:
-n = len(nums)
-maxSum = nums[0]
-minSum = sum = 0
-for i in range(n):
-sum += nums[i]
-maxSum = max(maxSum, sum - minSum)
-minSum = min(minSum, sum)
-
-return maxSum
+    def maxSubArray(self, nums: list[int]) -> int:
+        n = len(nums)
+        maxSum = nums[0]
+        minSum = sum = 0
+        for i in range(n):
+            sum += nums[i]
+            maxSum = max(maxSum, sum - minSum)
+            minSum = min(minSum, sum)
+
+        return maxSum
 ```
 
 _Javascript code_ from [**@lucifer**](https://github.com/azl397985856)
@@ -285,25 +288,31 @@ _Python3 code_
 ```python
 import sys
 class Solution:
-def maxSubArray(self, nums: List[int]) -> int:
-return self. helper(nums, 0, len(nums) - 1)
-def helper(self, nums, l, r):
-if l > r:
-return -sys. maxsize
-mid = (l + r) // 2
-left = self. helper(nums, l, mid - 1)
-right = self. helper(nums, mid + 1, r)
-left_suffix_max_sum = right_prefix_max_sum = 0
-sum = 0
-for i in reversed(range(l, mid)):
-sum += nums[i]
-left_suffix_max_sum = max(left_suffix_max_sum, sum)
-sum = 0
-for i in range(mid + 1, r + 1):
-sum += nums[i]
-right_prefix_max_sum = max(right_prefix_max_sum, sum)
-cross_max_sum = left_suffix_max_sum + right_prefix_max_sum + nums[mid]
-return max(cross_max_sum, left, right)
+    def maxSubArray(self, nums: list[int]) -> int:
+        return self. helper(nums, 0, len(nums) - 1)
+
+    def helper(self, nums, l, r):
+        if l > r:
+            return -sys. maxsize
+
+        mid = (l + r) // 2
+        left = self.helper(nums, l, mid - 1)
+        right = self.helper(nums, mid + 1, r)
+        left_suffix_max_sum = right_prefix_max_sum = 0
+        sum = 0
+
+        for i in reversed(range(l, mid)):
+            sum += nums[i]
+            left_suffix_max_sum = max(left_suffix_max_sum, sum)
+
+        sum = 0
+        for i in range(mid + 1, r + 1):
+            sum += nums[i]
+            right_prefix_max_sum = max(right_prefix_max_sum, sum)
+
+        cross_max_sum = left_suffix_max_sum + right_prefix_max_sum + nums[mid]
+
+        return max(cross_max_sum, left, right)
 ```
 
 _Javascript code_ from [**@lucifer**](https://github.com/azl397985856)
@@ -359,14 +368,15 @@ _Python3 code_
 
 ```python
 class Solution:
-def maxSubArray(self, nums: List[int]) -> int:
-n = len(nums)
-max_sum_ending_curr_index = max_sum = nums[0]
-for i in range(1, n):
-max_sum_ending_curr_index = max(max_sum_ending_curr_index + nums[i], nums[i])
-max_sum = max(max_sum_ending_curr_index, max_sum)
-
-return max_sum
+    def maxSubArray(self, nums: list[int]) -> int:
+        n = len(nums)
+        max_sum_ending_curr_index = max_sum = nums[0]
+
+        for i in range(1, n):
+            max_sum_ending_curr_index = max(max_sum_ending_curr_index + nums[i], nums[i])
+            max_sum = max(max_sum_ending_curr_index, max_sum)
+
+        return max_sum
 ```
 
 _Javascript code_ from [**@lucifer**](https://github.com/azl397985856)