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。
代码
public class Solution {
public boolean VerifySquenceOfBST(int [] sequence) {
if(sequence.length == 0)
{
return false;
}
else if(sequence.length == 1)
{
return true;
}
return VerifySequenceOfBST(sequence, 0, sequence.length - 1);
}
private boolean VerifySequenceOfBST(int [] sequence, int start, int end)
{
if(start >= end)
{
return true;
}
int i = start;
while(i < end && sequence[i] < sequence[end])
{
i++;
}
for(int j = i; j < end; j++)
{
if(sequence[j] < sequence[end])
{
return false;
}
}
return VerifySequenceOfBST(sequence, start, i - 1) && VerifySequenceOfBST(sequence, i, end - 1);
}
}