[Leetcode] Validate Binary Search Tree

/**
* 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) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
return isPartialBST(root, INT_MIN, INT_MAX);
}

bool isPartialBST(TreeNode* n, int minVal, int maxVal)
{
if (!n) return true;

if (n->val > minVal && n->val < maxVal)
{
return isPartialBST(n->left, minVal, n->val) && isPartialBST(n->right, n->val, maxVal);
}

return false;
}
};