So tree traversals...
Tree structure ------------------------------------- Root (A) ------------------------------------- L1 (B)(C) ------------------------------------- L2 (D)(E)(F)(G) ------------------------------------- L3 (H)(I)(J)(K) ------------------------------------- DFS in order traversal H D I B J E K A F C G ------------------------------------- DFS pre order traversal A B D H I E J K C F G ------------------------------------- DFS post order traversal B D H I E J K C F G A