app.js

/**
 * * 题目名称：删除最外层的括号
 * * 题目地址：https://leetcode-cn.com/problems/remove-outermost-parentheses
 */

// * 思路：
/**
 * @param {string} S
 * @return {string}
 */
var removeOuterParentheses = function (S) {
  const bracket = { '(': ')' }
  const stack = []
  let res = []
  const result = []
  for (let i = 0; i < S.length; i++) {
    const val = S[i]
    if (bracket[val]) { // 左括号
      stack.push(val)
    } else { // 右括号
      stack.pop()
    }
    if (stack.length === 0) {
      // 存在一组有效括号
      res.push(val)
      const cur = [...res]
      cur.shift()
      cur.pop()
      result.push(cur)
      res = []
      continue
    }
    res.push(val)
  }
  return result.flat().join('')
};

// 测试用例
let test = "(()())(())"

console.time('执行用时');
console.log(removeOuterParentheses(test));
console.timeEnd('执行用时');