Problem Description

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

An input string is valid if:

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

Examples

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 '()[]{}'.

解析

給定一個字串 s, 這個字串只會由 ‘(’, ‘)’, ‘[’,’]’,’{’,’}’ 六種字元所組成

定義字串 s 是 valid 如果符合以下條件：

1 對於每個 ‘(’, ‘[’, ‘{’ 三種字元，找得到在其右方找到對應的 ‘)’, ‘]’,’}’ 來做配對