Leetcode 98. Validate Binary Search Tree

文章作者:Tyan
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1. Description

Validate Binary Search Tree

2. Solution

  • Recurrent
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/**
* 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:
bool isValidBST(TreeNode* root) {
return validate(root, nullptr, nullptr);
}
private:
bool validate(TreeNode* root, TreeNode* max, TreeNode* min) {
if(!root) {
return true;
}
if((min && root->val <= min->val) || (max && root->val >= max->val)) {
return false;
}
return validate(root->left, root, min) && validate(root->right, max, root);
}
};

Reference

  1. https://leetcode.com/problems/validate-binary-search-tree/description/
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