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Validate_Binary_Search_Tree.cpp
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/*
Author: Timon Cui, [email protected]
Title: Validate Binary Search Tree
Description:
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.
Difficulty rating: Easy
Notes:
*/
/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
bool isValidBST(TreeNode *root, int low, int high) {
return !root || (root->val < high && root->val > low && isValidBST(root->left, low, root->val) && isValidBST(root->right, root->val, high));
}
bool isValidBST(TreeNode *root) {
return isValidBST(root, INT_MIN, INT_MAX);
}
};