Update 0053.最大子序和.md

Added python version code

problems/0053.最大子序和.md

@@ -142,7 +142,19 @@ Java：
 
 
 Python：
-
+```python
+class Solution:
+    def maxSubArray(self, nums: List[int]) -> int:
+        result = -float('inf')
+        count = 0
+        for i in range(len(nums)):
+            count += nums[i]
+            if count > result:
+                result = count
+            if count <= 0:
+                count = 0
+        return result
+```
 
 Go：