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Leetcode98.cpp
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90 lines (73 loc) · 2.46 KB
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// Leetcode98.cpp : This file contains the 'main' function. Program execution begins and ends there.
//
#include <iostream>
/**
* Definition for a binary tree node.
* 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) {}
* };
*/
bool isValidBST(TreeNode* root) {
bool res = true;
int min, max;
res = isValidBST(root, min, max);
return res;
}
bool isValidBST(TreeNode* root, int& min, int& max) {
bool res = true;
if (root->left == nullptr && root->right == nullptr) {
min = root->val; max = root->val; return true;
}
if (root->left)
{
if (root->left->val > root->val) return false;
int minL, maxL;
bool resLeft = isValidBST(root->left, minL, maxL);
res = res && resLeft && maxL < root->val; if (!res) return res;
min = minL;
}
else min = root->val;
if (root->right)
{
if (root->right->val < root->val) return false;
int minR, maxR;
bool resRight = isValidBST(root->right, minR, maxR);
res = res && resRight && minR > root->val; if (!res) return res;
max = maxR;
}
else max = root->val;
return res;
}
bool isbst(TreeNode* root, long min, long max) {
// Base Case
if (root == NULL) return true;
if (root->val > min && root->val < max) {
bool left = isbst(root->left, min, root->val);
bool right = isbst(root->right, root->val, max);
return left && right;
}
else {
return false;
}
}
bool isValidBST(TreeNode* root) {
return isbst(root, LONG_MIN, LONG_MAX);
}
int main()
{
std::cout << "Hello World!\n";
}
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu
// Tips for Getting Started:
// 1. Use the Solution Explorer window to add/manage files
// 2. Use the Team Explorer window to connect to source control
// 3. Use the Output window to see build output and other messages
// 4. Use the Error List window to view errors
// 5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
// 6. In the future, to open this project again, go to File > Open > Project and select the .sln file