# Valid Parentheses

Apr 7th, 2021
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1. class Solution:
2.     def isValid(self, s: str) -> bool:
3.         # Use list to represent stack
4.         stk = []
5.
6.         # Loop through string
7.         for c in s:
8.             # If opening paren, push paren onto stack
9.             if c == '(' or c == '[' or c == '{':
10.                 stk.append(c)
11.             # If closing paren
12.             elif c == ')' or c == ']' or c == '}':
13.                 # If stack is empty, return False
14.                 if not stk:
15.                     return False
16.                 # If top elem on stack is matching open paren, pop open paren from stack
17.                 if (c == ')' and stk[-1] == '(') or (c == ']' and stk[-1] == '[') or (c == '}' and stk[-1] == '{'):
18.                     stk.pop()
19.                 # Else, return False
20.                 else:
21.                     return False
22.
23.         # If stack is empty return True, else return False
24.         if not stk:
25.             return True
26.         return False