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

def isSametree(self, r, s):
if not r and not s:
return True
if r and s and r.val == s.val:
return self.isSametree(r.left, s.left) and self.isSametree(r.right, s.right)
return False

```

Uk01 on Feb 03, 2022 at 12:02 am

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