Valid Parentheses

21 Jul 2025 in Dev / Codingtest on CodingTest

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LeetCode Valid Parentheses

문제

Given a string s containing just the characters ‘(‘, ‘)’, ‘{‘, ‘}’, ‘[’ and ‘]’, determine if the input string is valid.

An input string is valid if:

Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Every close bracket has a corresponding open bracket of the same type.

예시

Example 1:

Input: s = “()”

Output: true

Example 2:

Input: s = “()[]{}”

Output: true

Example 3:

Input: s = “(]”

Output: false

Example 4:

Input: s = “([])”

Output: true

Example 5:

Input: s = “([)]”

Output: false

풀이

class Solution:
  def isValid(self, s: str) -> bool:
    valid = {
      ')': '(',
      '}': '{',
      ']': '['
    }
    stack = []

    for string in s:
      if string in valid.values():
        stack.append(string)
      else:
        if stack and valid[string] == stack[-1]:
          stack.pop()
        else:
          return False
    if stack:
      return False
    return True