Valid Parentheses

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.

 

Example 1:

Input: s = "()"
Output: true

Example 2:

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

Example 3:

Input: s = "(]"
Output: false

 

Constraints:

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

Solution(javascript)

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function(s) {
    let hash = {"(":")", "{":"}", "[":"]"};
    let stack = [];
    for (let i = 0; i < s.length; i++) {
        if(hash[s[i]]) {
            stack.push(s[i])
        } else {
            if (stack.length == 0) {
                return false;
            }
            let open = stack.pop();
            if (hash[open] != s[i]) {
                return false;
            }
        }
    }
    return stack.length === 0;
};