leeCode - 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:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.

 

Example 1:

Input: s = "()" Output: true

Example 2:

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

Example 3:

Input: s = "(]" Output: false

Example 4:

Input: s = "([)]" Output: false

Example 5:

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

 

Constraints:

• 1 <= s.length <= 104
• s consists of parentheses only '()[]{}'.

 

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풀이

 

const isValid = function (s) {
    let stack = [];
    const comp = {
        '(': ')',
        '{': '}',
        '[': ']'
    };

    for (let i = 0; i < s.length; i++) {
        if (comp[s[i]]) {
            stack.push(s[i]);
        } else {
            if (!stack.length) return false;
            if (comp[stack.pop()] !== s[i]) return false;
        }
    }
    return stack.length ? false : true
};