（二十三）二叉搜索树的后续遍历序列

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。

import java.util.Arrays;
public class Solution {
public boolean VerifySquenceOfBST(int [] sequence) {
    	if(sequence == null || sequence.length == 0){
    		return false;
    	}
    	int root = sequence[sequence.length - 1];
    	int i = 0;
    	for(;i< sequence.length -1;i++){
    		if(sequence[i] > root){
    			break;
    		}
    	}
    	int [] leftTree = Arrays.copyOfRange(sequence, 0, i);
    	int [] rightTree = Arrays.copyOfRange(sequence, i,sequence.length -1);
    	int j = i;
    	for(;j<sequence.length -1;j++){
    		if(sequence[j] < root){
    			return false;
    		}
    	}
    	
    	boolean left = true;
    	boolean right = true;
    	if(i > 0){
    		left = VerifySquenceOfBST(leftTree);
    	}
    	
    	if(i < sequence.length - 1){
    		right = VerifySquenceOfBST(rightTree);
    	}
    	
    	return (left&&right);
    }
}