二叉搜索树的后序遍历序列（Java实现）

public class E33VerifySequenceOfBST {
    //判断某一序列是否是二叉搜索树的后序遍历序列
    private class BinaryTreeNode{
        int value;
        BinaryTreeNode left;
        BinaryTreeNode right;
    }

    public static boolean verify(int[] sequence, int length){
        if (sequence == null || length <= 0)
            return false;

        return verifyCore(sequence,0, length - 1);
    }

    private static boolean verifyCore(int[] sequence, int start, int end){
        if (start >= end)
            return true;
        //根节点为最后一个元素
        int root = sequence[end];
        int i = 0;
        //找到左右子树分界点
        for (; i < end; i ++){
            if (sequence[i] > root)
                break;
        }
        //检验二叉搜索树
        for (int j = i; j < end; j ++){
            if (sequence[j] < root)
                return false;
        }
        //验证通过则继续寻找子节点
        boolean left = true;
        if (i > start)
            left = verifyCore(sequence, start, i - 1);
        boolean right = true;
        if (i < end)
            right = verifyCore(sequence, i, end - 1);
        return left && right;
    }
    //测试用例
    public static void main(String[] args){
        int[] sequence1 = {5, 7, 6, 9, 11, 10, 8};
        int[] sequence2 = {7, 4, 6, 5};
        System.out.println(E33VerifySequenceOfBST.verify(sequence1, 7)); //true
        System.out.println(E33VerifySequenceOfBST.verify(sequence2, 4)); //false
    }
}