Pergunta de entrevista da empresa Oracle

1) What are all the Tree traversals? Write output of tree traversals for a given tree. 2) Write code for inorder traversal of tree. 3) write code for checking parenthesis match. 4) write code for level order traversal of tree 5) write code for bubble sort. I have written a naive method solution. So I was asked to optimize it. He was satisfied with my solution. 6) what is normalisation?