##### Is This a Binary Search Tree? Hackerrank

For the purposes of this challenge, we define a binary search tree to be a binary tree with the following ordering requirements:

The data value of every node in a node’s left subtree is less than the data value of that node.

The data value of every node in a node’s right subtree is greater than the data value of that node.

Given the root node of a binary tree, can you determine if it’s also a binary search tree?

Complete the function in your editor below, which has 1 parameter: a pointer to the root of a binary tree. It must return a boolean denoting whether or not the binary tree is a binary search tree. You may have to write one or more helper functions to complete this challenge.

**Input Format**

You are not responsible for reading any input from stdin. Hidden code stubs will assemble a binary tree and pass its root node to your function as an argument.

**Constraints**

0<= data <= 10^{4}

**Output Format**

You are not responsible for printing any output to stdout. Your function must return true if the tree is a binary search tree; otherwise, it must return false. Hidden code stubs will print this result as a Yes or No answer on a new line.

**Sample Input**

**Sample Output**

No

##### Solution

/* 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; } */ bool check(Node* root, int maxLeft, int minRight) { if(!root) return true; if(root->data <= maxLeft || root->data >= minRight) return false; return check(root->left, maxLeft, root->data) && check(root->right, root->data, minRight); } bool checkBST(Node* root) { return check(root, -1, 10001); }

```
boolean checkBST(Node root, int minValue, int maxValue) {
if (root == null) {
return true;
}
if (root.data < minValue || root.data > maxValue) {
return false;
}
return ( checkBST(root.left, minValue, root.data - 1)
&& checkBST(root.right, root.data + 1, maxValue)
);
}
boolean checkBST(Node root) {
return checkBST(root, 0, 10000);
}
```

C++ bool checkBST(Node* root, int minValue, int maxValue) { if (root == NULL) { return true; } if (root->data < minValue || root->data > maxValue) { return false; } return ( checkBST(root->left, minValue, root->data - 1) && checkBST(root->right, root->data + 1, maxValue) ); } bool checkBST(Node* root) { return checkBST(root, 0, 10000); }

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