此处可输入以下树来进行调试。

构建的树为

1

/ | 2 3 4

/ | \ 5 6 7 B

| / 8 9 A

前序遍历:1 2 5 6 8 7 9 A 3 4 B

后序遍历:5 8 6 9 A 7 2 3 B 4 1

层次遍历:1 2 3 4 5 6 7 B 8 9 A-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