二叉树及按层遍历的算法实现

/******************************//  建立二叉树//  及按层遍历的算法实现 ******************************/#include<stdio.h>#include<stdlib.h>#include<string.h>#define size 256typedef char datatype;typedef struct node{datatype data;struct node *lchild;struct node *rchild;}*root,treenode;void init(root *t){(*t) = NULL;}void input(char *pre_str, char *in_str ){printf("please input the pre_order string:\n");gets(pre_str);printf("please input the in_order string:\n");gets(in_str);if(strlen(pre_str) != strlen(in_str)){puts("different string !!!");}}void build(char *pre_str,char *in_str,int len,root *t){if(pre_str == NULL || in_str == NULL)return ;(*t) = (root)malloc(sizeof(treenode));(*t)->data=*pre_str;(*t)->lchild=NULL;(*t)->rchild=NULL;if(len == 1)return ;char *first=in_str;char *move=in_str;int tmp_len=0;while((*pre_str) != *move){if(pre_str == NULL || move == NULL)return ;tmp_len++;if(tmp_len>len)break;move++;}int l_len,r_len;l_len = (int)(move-first);r_len = (len-l_len-1);if(l_len > 0)build(pre_str+1,in_str,l_len,&((*t)->lchild));if(r_len > 0)build(pre_str+1+l_len,in_str+1+l_len,r_len,&((*t)->rchild));}void travel_pre(root t){if(t == NULL)return ;printf("%c ",t->data);travel_pre(t->lchild);travel_pre(t->rchild);}void travel_in(root t){if(t == NULL)return ;travel_in(t->lchild);printf("%c ",t->data);travel_in(t->rchild);}void travel_post(root t){if(t == NULL)return ;travel_post(t->lchild);travel_post(t->rchild);printf("%c ",t->data);}void travel_level(root t){root quen[size];int front=-1;int rear=-1;rear++;quen[rear] = t;while(front != rear){root tmp;front=(front+1) % size;tmp=quen[front];printf("%c ",tmp->data);if(tmp->lchild != NULL){rear = (rear+1)%size;quen[rear]=tmp->lchild;}if(tmp->rchild != NULL){rear = (rear+1)%size;quen[rear]=tmp->rchild;}}}int main(void){root t;init(&t);int len;char pre_str[size];char in_str[size];input(pre_str,in_str);len = strlen(pre_str);build(pre_str,in_str,len,&t);printf("the pre_order is: \n");travel_pre(t);printf("\n");printf("the in_order is:\n");travel_in(t);printf("\n");printf("the post_order is:\n");travel_post(t);printf("\n");printf("the level_order is:\n");travel_level(t);printf("\n");return 0;}