LeetCode:Validate Binary Search Tree

题目链接

Given a binary tree, determine if it is a valid binary search tree (BST).

Assume a BST is defined as follows:

The left subtree of a node contains only nodes with keys less than the node's key.
The right subtree of a node contains only nodes with keys greater than the node's key.
Both the left and right subtrees must also be binary search trees.

分析：根据BST中序遍历序列有序的性质判断，只要在中序遍历二叉树的代码基础上加上判断相邻元素关系的语句即可本文地址

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  * int val;
 5  * TreeNode *left;
 6  * TreeNode *right;
 7  * TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     bool isValidBST(TreeNode *root) {
13         // IMPORTANT: Please reset any member data you declared, as
14         // the same Solution instance will be reused for each test case.
15         //注意题目要求是 less than和greater than;
16         stack<TreeNode*> S;
17         TreeNode *pre = NULL, *p = root;
18         while(p || S.empty() == false)
19         {
20             while(p)
21             {
22                 S.push(p);
23                 p = p->left;
24             }
25             if(S.empty() == false)
26             {
27                 p = S.top();
28                 S.pop();
29                 if(pre && p->val <= pre->val)return false;
30                 pre = p;
31                 p = p->right;
32             }
33         }
34         return true;
35     }
36 };

转载于:https://www.cnblogs.com/TenosDoIt/p/3448413.html

LeetCode:Validate Binary Search Tree相关推荐

LeetCode Validate Binary Search Tree(dfs)
问题:判断树是否是合法的二叉搜索树思路: 1.在dfs时,判断当前结点是否大于左子树的最大值,小于右子树的最小值.这是一种思路 2.另外一个思路是在中序遍历时,用个变量记录当前结点的前驱结点,再判断 ...
Leetcode: Validate Binary Search Tree
思路: 1. 难点在于构造递归函数的参数 2. 参数要包含上下界, 才能具有全局性. 第一次提交 WA 了, 因为写成来的判断函数是局部性的代码: const int POS = 1E9; cons ...
[CareerCup] 4.5 Validate Binary Search Tree 验证二叉搜索树
4.5 Implement a function to check if a binary tree is a binary search tree. LeetCode上的原题,请参见我之前的博客Va ...
LeetCode: 173. Binary Search Tree Iterator
LeetCode: 173. Binary Search Tree Iterator 题目描述 Implement an iterator over a binary search tree (BST ...
LeetCode 之 JavaScript 解答第98题 —— 验证二叉搜索树（Validate Binary Search Tree）
Time:2019/4/24 Title: Vaildata Binary Search Tree Difficulty: Medium Author: 小鹿题目:Vaildata Binary S ...
LeetCode Closest Binary Search Tree Value II
原题链接在这里:https://leetcode.com/problems/closest-binary-search-tree-value-ii/ 题目: Given a non-empty bin ...
[leetcode] Recover Binary Search Tree
Recover Binary Search Tree Two elements of a binary search tree (BST) are swapped by mistake. Recove ...
LeetCode ---　Validate Binary Search Tree
题目链接判断一颗二叉树是否是二叉搜索树(二叉排序树),也就是BST 如果该二叉树是BST, 那么对其中序遍历,所得序列一定是单调递增的(不考虑有重复数值的情况) 附上代码: 1 /** 2 * De ...
098 Validate Binary Search Tree 验证二叉搜索树
给定一个二叉树,判断其是否是一个有效的二叉搜索树. 一个二叉搜索树有如下定义: 左子树只包含小于当前节点的数. 右子树只包含大于当前节点的数. 所有子树自身必须也是二叉搜索树. ...

LeetCode:Validate Binary Search Tree

LeetCode:Validate Binary Search Tree相关推荐

最新文章

热门文章