# [LeetCode]#700. Search in a Binary Search Tree

**Environment: Python 3.8**

**Key technique: TreeNode**

Given the root node of a binary search tree (BST) and a value. You need to find the node in the BST that the node’s value equals the given value. Return the subtree rooted with that node. If such node doesn’t exist, you should return NULL.

For example,

Given the tree:

4

/ \

2 7

/ \

1 3And the value to search: 2

You should return this subtree:

`2 `

/ \

1 3

**Analysis:**

1. if root is nothing, return None.

2.if root.val is equal to val, return root.

3. if root.val >val, root=root.left

4.if root.val <val, root=root.right

**Solution:**

`class Solution:`

def searchBST(self, root, val):

if root is None:

return None

while root:

if root.val == val:

return root

elif root.val > val:

root = root.left

else:

root = root.right

return root

**Submissions:**

**Reference:**

https://leetcode.com/problems/search-in-a-binary-search-tree/discuss/997676/Python