0572: Subtree of Another Tree

Problem Statement

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

Code Solution

class Solution:
    def isSubtree(self, root, subRoot):
        def rec(src, tgt):
            if src and tgt:
                if rec(src.left, tgt):
                    return True
                if rec(src.right, tgt):
                    return True
                return src.val == tgt.val and rec(src.left, tgt.left) and rec(src.right, tgt.right)
            return src == tgt
            
        return rec(root, subRoot)