# Binary Search Tree Validation

Given a binary tree `root`

, return whether it’s a binary search tree. A binary tree `node`

is a binary search tree if :

- All nodes on its left subtree are smaller than
`node.val`

- All nodes on its right subtree are bigger than
`node.val`

- All nodes hold the these properties.

**Constraint**

`n ≤ 100,000`

where`n`

is the number of nodes in`root`

https://binarysearch.com/problems/Binary-Search-Tree-Validation

## Examples

### Example 1

**Input**

- root =

**Output**

- answer =
`False`

**Explanation**

This is not a binary search tree because the `7`

is not smaller than `5`

.

### Example 2

**Input**

- root =

**Output**

- answer =
`True`

## Leave a comment