A node is “good” if no node on the path from the root to that node has a strictly greater value. The root is always good (nothing above it). Count how many good nodes exist in the tree.
Look at this tree. Can you figure out which nodes are good just by inspecting their ancestors? Mark each one — then we'll see how you did.
Tap a node to cycle: unmarked ⟶ good (green ring) ⟶ not good (red ring) ⟶ unmarked. Mark ALL 7 nodes, then commit.
Some nodes are surprisingly hard to classify — the answer depends on more than just the node's own value. Try marking every node, then commit to see how you did.