20. Valid Parentheses
I had seen this problem before in "A Common-Sense Guide to Data Structures and Algorithms, Second Edition".
I used a deque for the Stack implementation.
class Solution:
def isValid(self, s: str) -> bool:
stack = deque()
close_chars = { ']': '[',
')': '(',
'}': '{'}
for x in s:
if x in close_chars:
if len(stack) <= 0:
return False
else:
popped = stack.pop()
if close_chars[x] != popped:
return False
else:
stack.append(x)
return len(stack) == 0
Last modified 1yr ago