添加0724寻找数组的中心索引 Python版本

problems/0724.寻找数组的中心索引.md

@@ -90,6 +90,15 @@ class Solution {
 ## Python
 
 ```python
+class Solution:
+    def pivotIndex(self, nums: List[int]) -> int:
+        numSum = sum(nums) #数组总和
+        leftSum = 0
+        for i in range(len(nums)):
+            if numSum - leftSum -nums[i] == leftSum: #左右和相等 
+                return i
+            leftSum += nums[i]
+        return -1
 ```
 
 ## Go