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。

python solution:

# -*- coding:utf-8 -*-
class Solution:
    def VerifySquenceOfBST(self, sequence):
        if len(sequence)==0:
            return False
        root = sequence[-1] #根节点的值
        for i in range(len(sequence)): #记录左右子树的分割点
            if sequence[i]>root:
                break
        for j in range(i,len(sequence)):
            if sequence[j]<root:
                return False
        left,right = True,True
        if i>0:
            left = self.VerifySquenceOfBST(sequence[:i])
        if i<len(sequence)-1:
            right = self.VerifySquenceOfBST(sequence[i:len(sequence)-1])
        return left and right