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leetcode-20. Valid parentheses -js version

2022-06-27 04:29:00 【Qianfan at the front】

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Code

/** *  Ideas ： Use stack  *  practice ： Traversal string  *  If it is an open parenthesis, it will be added to the stack ; *  If it is a right parenthesis, it matches the nearest character in the stack to see if it is paired ; *  If matching, the left parenthesis will be treated as a stack , Invalid mismatch proof string  */
var isValid = function(s) {
    
    let stack = [], length = s.length;
    if (length % 2) return false

    for (let item of s) {
    
        if (item === '{' || item === '[' || item === '(') {
    
            stack.push(item);
        } else {
    
            if (stack.length && stack.pop() === leftOf(item)) {
    
                continue;
            } else {
    
                return false;
            }
        }
    }

    return !stack.length;
};

var leftOf = function(s) {
    
    if (s === ')') return '(';
    if (s === ']') return '[';
    return '{';

}