链队列

　

#include<bits/stdc++.h>
#define OK 1
#define ERROR 0
using namespace std;typedef int Status;
typedef int ElemType;typedef struct QNode
{ElemType data;struct QNode *next;
}*Node;typedef struct
{Node front;Node rear;int len;
}LinkQueue;
///初始化
Status Init(LinkQueue &Q)
{Node p;p=(Node)malloc(sizeof(QNode));if(p){Q.front=Q.rear=p;p->next=NULL;Q.len=0;return OK;}elsereturn ERROR;
}
///判断队列是否为空
bool EmptyQueue(LinkQueue Q)
{if(Q.front == Q.rear){return true;}else{return ERROR;}
}
///入队
Status Push(LinkQueue &Q, ElemType e)
{Node p;p=(Node)malloc(sizeof(QNode));if(!p)exit(1);p->data=e;p->next=NULL; ///注意此处，刚开始没有想到，只有 p->next = NULL 才确定p是尾部Q.rear->next=p;Q.rear=p;Q.len++;return OK;
}
///出队
int Pop(LinkQueue &Q,ElemType &e)
{if(Q.front == Q.rear){printf("链队列没有元素\n");return ERROR;}else{Node p;p=Q.front->next;e=p->data;Q.front->next=p->next;if(Q.rear ==  p)Q.rear=Q.front;free(p);Q.len--;return e;}
}
///求队列长度
int QueueLength(LinkQueue Q)
{return Q.len;
}
///销毁队列
Status DestroyQueue(LinkQueue &Q)
{while(Q.front){Q.rear=Q.front->next;free(Q.front);Q.front=Q.rear;}return OK;
}///清空队列
Status ClearQueue(LinkQueue &Q)
{DestroyQueue(Q);Init(Q);return OK;
}/*另一种思路写法
Status ClearQueue(LinkQueue &Q)
{Node p,q;p=Q.front->next;while(p){q=p;p=p->next;free(q);}Q.rear=Q.front;Q.len=0;return OK;}另一种思路写法*/Status Print(LinkQueue Q)
{Node p;p=Q.front->next;while(p!=Q.rear){printf("%d--",p->data);p=p->next;}printf("%d\n",Q.rear->data);return OK;
}int main()
{int n;LinkQueue Q;Init(Q);printf("请输入入队元素(以0为结束标志)：");while(~scanf("%d",&n)){if(n == 0)break;Push(Q,n);}if(EmptyQueue(Q))printf("YES,kong\n");elseprintf("NO kong\n");printf("队列的长度为：%d\n",QueueLength(Q));printf("遍历队首到队尾的元素：\n");Print(Q);printf("------------------------------\n");int e;printf("出队的队首元素为：%d\n",Pop(Q,e));printf("队列的长度为：%d\n",QueueLength(Q));printf("遍历队首到队尾的元素：\n");Print(Q);printf("------------------------------\n");printf("Clear queue...\n");ClearQueue(Q);if(EmptyQueue(Q))printf("YES,kong\n");elseprintf("NO kong\n");printf("------------------------------\n");return 0;
}
/*
1 2 3 4 5 0
*/