572. Subtree of Another Tree

Easy

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.

Solution

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.isSameTree(root, subRoot):
            return True

        return self.isSubtree(root.left, subRoot) or self.isSubtree(root.right, subRoot)

    def isSameTree(self, root: Optional[TreeNode], subRoot: Optional[TreeNode]) -> bool:
        if root is None and subRoot is None:
            return True

        if root is None or subRoot is None:
            return False

        if root.val != subRoot.val:
            return False

        return self.isSameTree(root.left, subRoot.left) and self.isSameTree(
            root.right, subRoot.right
        )


class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right