g0001_0100.s0098_validate_binary_search_tree.Solution.c Maven / Gradle / Ivy

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104 LeetCode algorithm problem solutions

There is a newer version: 1.8

// #Medium #Top_100_Liked_Questions #Top_Interview_Questions #Depth_First_Search #Tree #Binary_Tree
// #Binary_Search_Tree #Data_Structure_I_Day_14_Tree #Level_1_Day_8_Binary_Search_Tree
// #Udemy_Tree_Stack_Queue #Big_O_Time_O(N)_Space_O(log(N))
// #2024_11_02_Time_0_ms_(100.00%)_Space_11.9_MB_(57.64%)

#include 
#include 
#include 

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
// Helper function to check if the tree is a valid BST
bool solve(struct TreeNode* root, long left, long right) {
    if (root == NULL) {
        return true;
    }
    if (root->val <= left || root->val >= right) {
        return false;
    }
    return solve(root->left, left, root->val) && solve(root->right, root->val, right);
}

// Main function to check if a tree is a valid BST
bool isValidBST(struct TreeNode* root) {
    return solve(root, LONG_MIN, LONG_MAX);
}