Introduction - If you have any usage issues, please Google them yourself
Enter the character sequence to build the binary tree. (2) first order, in sequence, after the binary tree traversal: a recursive algorithm. (3) The first tree traversal: non-recursive algorithm (the best can achieve in sequence, after the non-recursive algorithm). (4) Find the number of leaves of the binary tree. (5) the level of aid queue binary tree traversal. (6) Design a simple menu in the main function, namely to debug these algorithms.