用js刷剑指offer(二叉搜索树的后序遍历序列)

题目描述

输入一个整数数组，判断该数组是不是某二叉搜索树的后序遍历的结果。如果是则输出Yes,否则输出No。假设输入的数组的任意两个数字都互不相同。

牛客网链接

js代码

function VerifySquenceOfBST(sequence)
{
    // write code here
    if (sequence.length === 0) return false
    let length = sequence.length
    let root = sequence[length-1]
    let mid = 0
    let flag = false
    for (let i = 0; i < length; i++) {
        if (root < sequence[i]) {
            mid = i
            flag = true
            break
        }
    }
    for (let i = mid; i < length; i++){
        if (root > sequence[i] && flag) {
            return false
        }
    }
    let left = true
    if (mid > 0) {
        left = VerifySquenceOfBST(sequence.slice(0, mid))
    }
    let right = true
    if (mid < sequence.length-1){
        right = VerifySquenceOfBST(sequence.slice(mid, length-1))
    }
    return  left && right 
}