## DEV Community

Abhishek Chaudhary

Posted on

# Subtree of Another Tree

Given the roots of two binary trees `root` and `subRoot`, return `true` if there is a subtree of `root` with the same structure and node values of `subRoot` and `false` otherwise.

A subtree of a binary tree `tree` is a tree that consists of a node in `tree` and all of this node's descendants. The tree `tree` could also be considered as a subtree of itself.

Example 1:

Input: root = [3,4,5,1,2], subRoot = [4,1,2]
Output: true

Example 2:

Input: root = [3,4,5,1,2,null,null,null,null,0], subRoot = [4,1,2]
Output: false

Constraints:

• The number of nodes in the `root` tree is in the range `[1, 2000]`.
• The number of nodes in the `subRoot` tree is in the range `[1, 1000]`.
• `-104 <= root.val <= 104`
• `-104 <= subRoot.val <= 104`

SOLUTION:

``````# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
if not p or not q:
if p or q:
return False
return True
if p.val == q.val and self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right):
return True

def isSubtree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool:
if self.isSameTree(root, subRoot):
return True
if not root or not subRoot:
return False
return self.isSubtree(root.left, subRoot) or self.isSubtree(root.right, subRoot)
``````