[20] 有效的括号

/**
 * @param {string} s
 * @return {boolean}
 */
var isValid = function (s) {
  let stack = [];
  for (let c of s) {
    if (c === '(') {
      stack.push(')');
    } else if (c === '[') {
      stack.push(']');
    } else if (c === '{') {
      stack.push('}');
    } else if (c === '\'') {
      if (stack.length === 0 || c !== stack[stack.length - 1]) {
        stack.push('\'');
      } else {
        stack.pop();
      }
    } else if (stack.length === 0 || c !== stack.pop()) {
      return false;
    }
  }
  return stack.length === 0;
};