572. Subtree of Another Tree

Easy

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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

# 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 subRoot is None:
            return True
        if root is None:
            return False
        if self.compare(root,subRoot):
            return True
        return self.isSubtree(root.left,subRoot) or self.isSubtree(root.right, subRoot)
    
    def compare(self, root, subRoot):
        if root is None and subRoot is None:
            return True
        if root is None or subRoot is None:
            return False
        return root.val == subRoot.val and self.compare(root.left,subRoot.left) and self.compare(root.right, subRoot.right)