题解 | #找到搜索二叉树中两个错误的节点#

/**
 * struct TreeNode {
 *    int val;
 *    struct TreeNode *left;
 *    struct TreeNode *right;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 the root
     * @return int整型vector
     */
    vector<int> res{-1, -1};
    TreeNode* pre = NULL;
    void helper(TreeNode* root){
        if(root == NULL) return;
        helper(root -> left);
        if(pre != NULL && pre -> val > root -> val && res[1] == -1) res[1] = pre -> val;
        if(pre != NULL && pre -> val > root -> val && res[1] != -1) res[0] = root -> val;
        pre = root;
        helper(root -> right);
    }
    vector<int> findError(TreeNode* root) {
        // write code here
        helper(root);
        return res;
    }
};