Same Tree

Two binary trees are the same if they have the same shape and the same value in every corresponding node. Check it.

Tree format. A binary tree is given on one line in level order (top to bottom, left to right), with null for a missing child — the same way most interview platforms show trees. Trailing nulls are left out, and an empty tree is the single word null. Example: 3 9 20 null null 15 7 is

    3
   / \
  9   20
     /  \
    15   7

Input: two trees, one per line.

Output: true or false.

Constraints: 0 ≤ nodes ≤ 10⁴ per tree. The tree has at most 10⁴ nodes and its height is at most 500, so recursion is safe in every language.

Think about it: both empty → same; one empty → different; otherwise compare the values and recurse on left/left and right/right.