LeetCode 337 House Robber III - Problem Statement

Houses form a binary tree. Each house has money. You cannot rob two directly connected houses (parent and child). Find the maximum money you can rob. Example: Tree $[3, 2, 3, \text{null}, 3, \text{null}, 1]$.

If you rob the root ($3$), you cannot rob its children ($2$ and $3$). The best is $3+3+1=7$: take the root and two grandchildren. This is House Robber on a tree. For each node, you decide: rob it or skip it?