285. Inorder Successor in BST

Given a binary search tree and a node in it, find the in-order successor of that node in the BST.

一刷
题解：
类似于binary search，我们要找一个大于该点的最小值。

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode inorderSuccessor(TreeNode root, TreeNode p) {
        if(root == null) return null;
        if(root.val

二刷

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public TreeNode inorderSuccessor(TreeNode root, TreeNode p) {
        if(root == null) return null;
        if(root.val<=p.val) return inorderSuccessor(root.right, p);
        else{
            TreeNode left = inorderSuccessor(root.left, p);
            if(left == null) return root;
            else return left;
        }   
    }
}