(Programming training) Let's look back again. The data structure is the pre-order, middle-order, and post-order traversal (recursion) of the binary tree, and then let's look back at the binary tree.

(Programming training) Let's look back again. The data structure is the pre-order, middle-order, and post-order traversal (recursion) of the binary tree, and then let's look back at the binary tree.

I recently reviewed the data structure and took a look at the code I wrote in my freshman year. After reading the code, I had a deeper understanding than I had at the beginning.

I hope this will provide some reference for beginners.

It can be run in VC ++ 6.0, and many comments have been written at the beginning.

[Problem description]

Create a binary tree binary linked list based on the sequential storage structure, and traverse the binary tree in ascending, middle, and back order.

[Basic requirements]

· Function: Create a binary tree binary linked list based on the sequential storage structure, and perform sequential, central, and post-sequential traversal.

· Input: sequential storage of input binary trees.

· Output: the first, middle, and last traversal sequences of Binary Trees.

[Test Data]

The input binary tree is stored sequentially, and the sequence number and value of each node are given,

1A

2B

3C

4D

6E

7F

9G

12 H

14I

15J

00

The expected output is the binary tree created accordingly.

Sequence: ABDGCEHFIJ,

Central sequence: DGBAHECIFJ,

Post-sequence: GDBHEIJFCA.

[Module division]

Four modules are designed in total

(1) create a binary linked list CreateBT ();

(2) First traverse the binary tree PreOrder ():

(3) traverse the binary tree InOrder () in ascending order ():

(4) Post-order traversal of Binary Tree PostOrder ():

/* Binary tree traversal */# include <stdio. h> # include <malloc. h> typedef char ElemType; // define the data structure typedef struct BNode {ElemType data; struct BNode * lchild; struct BNode * rchild;} BTNode, * BinTree; // create BinTree CreatBT () {BTNode * q, * ptr [20]; int I, j; ElemType x; BinTree root = NULL; scanf ("% d % c", & I, & x); getchar (); while (x! = '') {Q = (BTNode *) malloc (sizeof (BTNode); q-> data = x; q-> lchild = NULL; q-> rchild = NULL; ptr [I] = q; if (1 = I) root = q; else {j = I/2; if (! (I % 2) // left subtree ptr [j]-> lchild = q; else // right subtree ptr [j]-> rchild = q ;} scanf ("% d % c", & I, & x); getchar ();} return root;} // first traverse void PreOrder (BinTree root) {if (root! = NULL) {printf ("% c", root-> data); PreOrder (root-> lchild); PreOrder (root-> rchild );}} // traverse void InOrder (BinTree root) {if (root! = NULL) {InOrder (root-> lchild); printf ("% c", root-> data); InOrder (root-> rchild );}} // traverse void PostOrder (BinTree root) {if (root! = NULL) {PostOrder (root-> lchild); PostOrder (root-> rchild); printf ("% c", root-> data );}} // main function int main (void) {BinTree root; root = CreatBT (); printf ("sequential traversal \ n"); PreOrder (root ); printf ("\ n"); printf ("sequential traversal \ n"); InOrder (root); printf ("\ n "); printf ("sequential traversal \ n"); PostOrder (root); printf ("\ n"); return 0 ;}

Running result