[Leetcode] 0020. Valid Parentheses

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内容目录

Easy

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.

Example 1:

Input: s = "()"
Output: true

Example 2:

Input: s = "()[]{}"
Output: true

Example 3:

Input: s = "(]"
Output: false

Constraints:

1 <= s.length <= 10 ⁴
s consists of parentheses only '()[]{}'.

Python

				
					# time complexity: O(n) # space complexity: O(n) class Solution: def isValid(self, s: str) -> bool: bracketMap = {"(": ")", "[": "]", "{": "}"} openSet = set(["(", "[", "{"]) stack = [] for char in s: if char in openSet: stack.append(char) elif stack and char == bracketMap[stack[-1]]: stack.pop() else: return False return stack == [] Input = "(())" print(Solution().isValid(Input))

Easy

Python

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