今天写这题

https://www.acwing.com/problem/content/submission/code_detail/36912299/

java

class Solution {
    public boolean verifySequenceOfBST(int [] sequence) {
        if (sequence == null || sequence.length == 0) {
            return true;
        }
        return verify(sequence, 0, sequence.length - 1);
    }

    private boolean verify(int[] postorder, int start, int end) {
        if (start >= end) {
            return true;
        }

        int root = postorder[end];
        int i = start;

        // 找到第一个大于根节点的元素，这个元素之前的部分是左子树
        while (i < end && postorder[i] < root) {
            i++;
        }

        // 检查右子树中的所有元素是否都大于根节点
        for (int j = i; j < end; j++) {
            if (postorder[j] < root) {
                return false;
            }
        }

        // 递归检查左子树和右子树
        return verify(postorder, start, i - 1) && verify(postorder, i, end - 1);
    }

}