validParentheses

validParentheses.js

/**
 * Valid Parentheses
 * @param {string} s
 * @return {boolean}
 */
const validParentheses = (s) => {
  if (s === null || !s.length) return true;

  const chars = s.split('');
  const stack = [];

  for (const c of chars) {
    if (c === '[') stack.push(']');
    else if (c === '{') stack.push('}');
    else if (c === '(') stack.push(')');
    else if (!stack.length || c !== stack.pop()) return false;
  }

  return stack.length === 0;
};