Look for these signals in the problem:
- Hierarchical data structure given: When the problem provides a tree, traversal patterns (preorder, inorder, postorder, level-order) apply directly.
- "Subtree" in problem statement: Problems involving subtrees naturally decompose into recursive subproblems.
- BST property mentioned: Binary Search Trees enable search by eliminating half the tree each step.
- "Path" from root or between nodes: Tree paths are found by combining paths through ancestors and descendants.
- "Depth" or "height" calculations: Recursively compute depth as plus max child depth.