剑指offer（20）-二叉搜索树的后序遍历序列

题目描述

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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。

代码

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class Solution {public:    bool VerifySquenceOfBST(vector<int> sequence) {        int size = sequence.size();        if(0==size)        {            return false;        }        return isLastOrder(sequence, 0, size-1);    }private:    bool isLastOrder(vector<int>& sequece, int b, int e)    {        if(b==e)        {            return true;        }        int mid = b;        while(sequece[mid++]<sequece[e] && mid<e);        int tmp = mid;        while (sequece[tmp++]>sequece[e] && tmp<e);        if(tmp<e)        {            return false;        }        if(mid==b || mid==e)        {            return isLastOrder(sequece, b, e-1);        }        else        {            return (isLastOrder(sequece, b, mid-1) && isLastOrder(sequece, mid, e-1));        }    }};