Data structure---C-language implementation clue two fork tree

Clue two fork tree, here on the basis of the binary tree added a clue//Xin Yang # include <stdio.h> #include <stdlib.h>typedef char elemtype; typedef enum {Link,thread} Childtag;  Link represents the node, thread represents the clue typedef struct bitnode{elemtype data;  struct Bitnode *lchild, *rchild; int Ltag, Rtag;} Bitnode, *bittree;bittree Pre; Create a global variable that represents the node you just visited/* Create a two-fork tree whose input must follow the order of the pre-order traversal. T: Two fork root node arr: The values of each node in the order of the preceding sequence traversal.  No child nodes with a space instead of */void create_tree (Bittree *t, char **arr) {char C; SSCANF (*arr, "%c", &c);  Read in a node value (*arr) + +;    if ("= = = c)//If it is a space, indicates an empty node {*t=null;      } else {*t= (bittree) malloc (sizeof (Bitnode));//Construct new node (*t)->data=c;      (*t)->ltag=link;      (*t)->rtag=link; Create_tree (& (*T)->lchild,arr)///construct a new node for the left Child Create_tree (& (*t)->rchild,arr);//Construct new node right child}}/* Access node information */ void visit (Bittree T) {printf ("| %d | %c | %d |\n ", T->ltag,t->data,t->rtag);}      /* Pre-order traversal accesses the binary tree */void pre_order_traverse (bittree t,int level) {if (t) {visit (T);     Pre_order_traverse (t->lchild,level+1); Pre_order_traverse (t->rchild,level+1);      }}/* traversing a binary tree, */void in_order_threading (Bittree t) {if (t) {in_order_threading (t->lchild);//left child threaded if (!      T->lchild)//If the left child is empty, point it to the direct precursor {t->lchild=pre;    t->ltag=thread; } if (!pre->rchild)//If the right child of the previous node is empty, it points to the direct successor.      (Note: Only access to the next node will be known to the successor of this node.) {pre->rchild=t;    pre->rtag=thread;      } pre=t; In_order_threading (T->rchild); Right child clue}}/* joins a head node to make a two-fork clue tree into a closed ring P: a two-fork tree with a head node. The left child of the head node points to a binary tree T; the right child points to the last leaf node in the T-tree: Two-tree without a head node.  */void in_thread (bittree *p,bittree T) {(*p) = (bittree) malloc (sizeof (Bitnode));//Construct a newly added head node (*p)->ltag=link;  (*p)->rtag=thread;  (*p)->rchild=*p; if (!    T)//If the binary tree is empty, then the child of P points to itself.    {(*p)->lchild=*p;      } else {(*p)->lchild=t;      Pre=*p; In_order_threading (T); The two-fork tree is threaded (*p)->rchild=pre; Point the head node right child to the last leaf knot pre->rtag=thread; Point the last leaf node's right child to the head node.      In this way, the ring is formed.    pre->rchild=*p; }}/* non-recursive mode: Middle sequence traversal twoA fork tree (the tree must have a head node and is already threaded) P: Two-tree with head node */void in_order_traverse (Bittree P) {Bittree T;  t=p->lchild;      while (T!=P)//Determine if the empty tree {while (T->ltag==link)//starts from the left child until the leaf node {t=t->lchild;}      Visit (T); while (T->rtag==thread && t->rchild!=p)//According to the clue, access the successor node.  And the successor node is not the {t=t->rchild; that points to the head node.      Visit (T);}    t=t->rchild;  }}int Main () {Bittree p,t; int level = 1; Represents the depth of the node char *arr= "AB D CE"; Create_tree (&t,&arr) for constructing a two-fork tree with the required nodes (entered as a pre-order traversal method);  Constructs a two-fork tree printf ("Pre_order_traverse: First order traversal: \ n"); Pre_order_traverse (T,level);  Pre-sequence traversal output binary tree printf ("In_order_traverse: Middle sequence traversal: \ n"); In_thread (&p,t); Binary Tree-threaded in_order_traverse (P); Outputs a threaded two-tree return of 0;}

Data structure---C-language implementation clue two fork tree