找到最长的回文子串

const loopCompare = (leftIndex, rightIndex, arr, workStorage) =>{
    if(arr[leftIndex] === arr[rightIndex]){
      workStorage.unshift(arr[leftIndex])
      workStorage.push(arr[rightIndex])
    }
    if(arr[leftIndex - 1] && arr[rightIndex + 1]){
      loopCompare(leftIndex - 1, rightIndex + 1, arr, workStorage)
    }
    return;
  }

  const getStrLen = (str) =>{
    const arr = str.split('');
    let res = {};
    if(arr.length === 1 || arr.length === 0){
      return str
    }
    arr.map((char, index) =>{
      let workStorage = {
        o: [],
        j: []
      }
      if(arr[index + 1] && char === arr[index + 1]){//偶数对称
        loopCompare(index, index+1, arr, workStorage.o)
      }
      if(arr[index -1] && arr[index + 1] && (arr[index -1] === arr[index + 1])){//奇数对称
        workStorage.j.push(char)
        loopCompare(index-1, index+1, arr, workStorage.j)
      }
      if(workStorage.o.length === 0 && workStorage.j.length === 0){
        workStorage.j.push(char)
      }
      res[index] = {
        workStorage: workStorage.j.length > workStorage.o.length ? workStorage.j : workStorage.o,
        str: workStorage.j.length > workStorage.o.length ? workStorage.j.join('') : workStorage.o.join(''),
        length: workStorage.j.length > workStorage.o.length ? workStorage.j.length : workStorage.o.length
      }
    })
    const max = Object.values(res).reduce((max, c) =>max?.length > c?.length ? max : c)
    return max.str
  }

console.log(getStrLen('abbaccccccca'))