【LeetCode】285.Inorder Successor in BST(Medium)(带锁题)解题报告

【LeetCode】285.Inorder Successor in BST(Medium)(带锁题)解题报告

题目地址：https://leetcode.com/problems/inorder-successor-in-bst/

题目描述：

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

  Note: If the given node has no in-order successor in the tree, return null.

Solution:

/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }找的是比这个node大的最小值
* 迭代
time : O(h)
space : O(1)
*/
class Solution {
int res = 0;
int height = 0;
public TreeNode inorderSuccessor(TreeNode root,TreeNode p) {
TreeNode res = null;
while(root ！= null){
if(root.val <= p.val){
root = root.right;
}else{
res = root;
root = root.left;
}
}
return res;
}
}

Solution2：

/**
* Definition for a binary tree node.
* public class TreeNode {
*     int val;
*     TreeNode left;
*     TreeNode right;
*     TreeNode(int x) { val = x; }
* }递归
time : O(h)
space : O(n)
*/
class Solution {
public TreeNode inorderSuccessor(TreeNode root,TreeNode p){
if(root == null) return null;
if(root.val <= p.val){
return successor(root.right,p);
}else{
TreeNode temp = successor(root.left,p);

return res;
}
}

Date：2018年3月19日