main.cpp

Go to the documentation of this file.

#include <iostream>
#include <vector>
#include <stack>
#include <algorithm>
 
using namespace std;
 
struct TreeNode
{
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode() : val(0), left(nullptr), right(nullptr) {}
    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
    TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
};
 
class Solution
{
public:
    bool isValidBST(TreeNode* root)
    {
        return validate(root, nullptr, nullptr);
    }
 
private:
    bool validate(TreeNode* node, TreeNode* min_node, TreeNode* max_node)
    {
        if (!node)
            return true;
        if ((min_node && node->val <= min_node->val) || (max_node && node->val >= max_node->val))
            return false;
        return validate(node->left, min_node, node) && validate(node->right, node, max_node);
    }
};
 
void delete_tree(TreeNode* root)
{
    if (root == nullptr)
        return;
    delete_tree(root->left);
    delete_tree(root->right);
    delete root;
}
 
int main()
{
    // TreeNode* root = new TreeNode(5, new TreeNode(1), new TreeNode(4, new TreeNode(3), new TreeNode(6)));
    // TreeNode* root = new TreeNode(5, new TreeNode(1), new TreeNode(6, new TreeNode(3), new TreeNode(7)));
    // TreeNode* root = new TreeNode(2, new TreeNode(1), new TreeNode(3));
    TreeNode* root = new TreeNode(5, new TreeNode(4), new TreeNode(6, new TreeNode(3), new TreeNode(7)));
    Solution sol;
    cout << "output: " << sol.isValidBST(root) << endl;
    delete_tree(root);
    return 0;
}