数据结构_归并排序

//归并排序
  class ArrayList {
    constructor () {
      this.array = []
    }
    insert (data) {
      return this.array.push(data)
    }
    mergeSort () {
      this.array = this.merge_1(this.array)
    }
    //辅助函数1；分数组，直到一个数为一个数组
    merge_1 (arr) {
      //获取数组长度
      let length = arr.length
      if (length > 1) {
        let index = Math.floor(length / 2)
        let left = arr.slice(0, index)
        let right = arr.slice(index)
        console.log(arr)
        return this.merge_2(this.merge_1(left), this.merge_1(right))
      }
      else return arr
    }
    // 辅助函数2： 合并数组，返回合并后的数组
    merge_2 (leftArr, rightArr) {
      let mergeArr = []
      // while (leftArr[0] && rightArr[0]) {
      while (leftArr.length && rightArr.length) {
        if (leftArr[0] > rightArr[0]) mergeArr.push(rightArr.shift())
        else mergeArr.push(leftArr.shift())
      }
      return mergeArr.concat(leftArr, rightArr) 
    }
  }
  let arr = new ArrayList()
  arr.insert(9)
  arr.insert(5)
  arr.insert(8)
  arr.insert(0)
  arr.insert(1)
  arr.insert(6)
  arr.insert(4)
  arr.insert(7)
  arr.insert(3)
  arr.insert(2)