This is a weird problem - feels the need to explain to you what an inorder traversal is, except it does this in a shockingly weird and stilted way when it could've just linked wikipedia. I shudder to think this was someone's first contact with graph traversal, they must've come away with the impression that it's some inescrutable technical bullshit when it's one of the simplest things in cs. Also as per usual problem does a poor job of specifying how indexes work (e.g. here root is at depth 1). Also remember to set the recursion limit to something decently high if you're using python