Introduction - If you have any usage issues, please Google them yourself
Here you can enter the following tree for debugging. Construction of the tree 1/| \ 2 3 4/| \ \ 5 6 7 B |/\ before 8 9 A preorder: 1256879 A 3 4 B after preorder: 5 8 6 9 A 7 2 3 B 4 1 level traversal: 1 2 3 4 5 6 7 B 8 9 A