Problem

Given the roots of two binary trees, root and subRoot, determine if subRoot is a subtree of root.

A subtree consists of a node in the tree and all its descendants.

Example 1

checkSubtree([1, 2, 3, null, null, 4], [3, 4])
// return true

Example 2

checkSubtree([1, 2, 3, null, null, 4, 5], [3, 4, 6])
// return false