一步一步复习数据结构和算法基础-层次建立层次遍历二叉树

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define maxnum 100
#define maxitem 1024
typedef struct node
{
char data;
struct node *lchild,*rchild;
}btree;
typedef btree* QElemType;

//队列元素
typedef struct QNode
{
QElemType data;
struct QNode *next;
}QNode,*QueuePtr;

//队列
typedef struct
{
QueuePtr front,rear;
}LinkQueue;

btree *Q[maxnum];
btree *CreatTree(char str[])
{
int i=0;
int front=1,rear=0;
btree *root,*s;
root = NULL;	//树根
while(str[i] != '#')		//如果遇到#意味着输入结束
{
s = NULL;
if(str[i] != '@')		//@符号代表NULL
{
s = (btree*)malloc(sizeof(btree));
s->data = str[i];
s->lchild = NULL;
s->rchild = NULL;
}
rear ++;
Q[rear] = s;
if(rear == 1)root = s;
else
{
if(s && Q[front])
if(rear % 2 == 0)
Q[front]->lchild = s;
else
Q[front]->rchild = s;
if(rear % 2 == 1)front++;

}
i++;
}

return root;
}

//初始化队列
int InitQueue(LinkQueue *Q)
{
(*Q).front = (*Q).rear = (QueuePtr)malloc(sizeof(QNode));
if(!(*Q).front)exit(1);
(*Q).front->next = NULL;
return 1;
}

//判断队列是否为空
int QueueEmpty(LinkQueue Q)
{
if(Q.front == Q.rear)return 1;
else return 0;
}

//进入队列
int EnQueue(LinkQueue *Q,QElemType e)
{
QueuePtr p = (QueuePtr)malloc(sizeof(QNode));
if(!p)exit(1);
p->data = e;
p->next = NULL;
(*Q).rear->next = p;
(*Q).rear = p;
return 1;
}

//出队列
int DeQueue(LinkQueue *Q,QElemType *e)
{
QueuePtr p;
if((*Q).front == (*Q).rear)return 0;
p = (*Q).front->next;
*e = p->data;
(*Q).front->next = p->next;

if((*Q).rear == p)
(*Q).rear = (*Q).front;
free(p);
return 1;
}

//层次遍历二叉树
void LevelOrderTree(btree *root)
{
LinkQueue q;
QElemType a;
if(root)
{
InitQueue(&q);
EnQueue(&q,root);
while(!QueueEmpty(q))
{
DeQueue(&q,&a);
printf("%c ",a->data);
if(a->lchild != NULL)
EnQueue(&q,a->lchild);
if(a->rchild != NULL)
EnQueue(&q,a->rchild);
}

printf("\n");
}
}

//销毁树
void DestroyTree(btree *root)
{
if(root == NULL)return ;
if(root)
{
DestroyTree(root->lchild);
DestroyTree(root->rchild);
}
free(root);
root = NULL;
}
int main()
{
btree *root;
char str[maxitem];
gets(str);
strcat(str,"#");
root = CreatTree(str);
LevelOrderTree(root);
DestroyTree(root);
return 0;

}