Introduction - If you have any usage issues, please Google them yourself
1) Use a preorder traversal sequence construction algorithm, using the linked list of binary, indicating that the arithmetic expression 2* 3+6/3 of identifier tree
2) Find the identifier tree preorder, inorder, postorder sequence, stored in the array and display the results
3) Find the number of leaf nodes in the tree
Additional: 3) Use the order sequence to evaluate the expression (using a stack implementation)