isBST? V2

/* Hidden stub code will pass a root argument to the function below. Complete the function to solve the challenge. Hint: you may want to write one or more helper functions.

The Node struct is defined as follows:
    struct Node {
        int data;
        Node* left;
        Node* right;
    }
*/

#include <limits.h>

int find_max(Node* root){
    if (!root)  return INT_MIN;
    int max_right = find_max(root->right);
    int max_left = find_max(root->left);
    return max(max(max_right, max_left), root->data);
}

int find_min(Node* root){
    if (!root)  return INT_MAX;
    int min_right = find_min(root->right);
    int min_left = find_min(root->left);
    return min(min(min_right, min_left), root->data);
}

bool checkBST(Node* root) {
    if (!root) return true;

    if(root->left && find_max(root->left) >= root->data)
        return false;

    if(root->right && find_min(root->right) <= root->data)
        return false;

   return checkBST(root->right) && checkBST(root->left);
}