[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Author: pre-commit-ci[bot]

algorithms/valid-parentheses.py

@@ -1,10 +1,10 @@
 class Solution:
     def isValid(self, s):
         stack = []
-        mapping = {')': '(', '}': '{', ']': '['}
+        mapping = {")": "(", "}": "{", "]": "["}
         for char in s:
             if char in mapping:
-                top = stack.pop() if stack else '#'
+                top = stack.pop() if stack else "#"
                 if mapping[char] != top:
                     return False
             else: