面试题 04.06 找出二叉搜索树中指定节点的“下一个”节点

题目：

 

 

解答：

 

 

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* inorderSuccessor(TreeNode* root, TreeNode* p) 
    {
        if (root == NULL || p == NULL) 
        {
            return NULL;
        }
        if (p->val >= root->val) 
        {
            return inorderSuccessor(root->right, p);
        } 
        else 
        {
            TreeNode* left = inorderSuccessor(root->left, p);
            return left ? left : root;
        }
    }
};