数据结构实验之队列一:排队买饭

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
typedef struct node
{
int data;
node *next;
}*qtype;
typedef struct
{
qtype front,rear;
int length;
} que;

int QueInitial(que &q)
{
q.front=q.rear=(qtype)malloc(sizeof(node));
q.front->next=NULL;
q.length=0;
return 1;
}

void InQue(que &q,int e)
{
qtype p;
p=(qtype)malloc(sizeof(node));
p->data=e;
p->next=NULL;

q.rear->next=p;
q.rear=p;
q.length++;
}

int DelQue(que &q)
{
qtype p;
if(q.front==q.rear) return 0;

p=q.front->next;
q.front->next=p->next;

if(q.rear==p) q.rear=q.front;
//若是最后一个元素，尾指针指向头指针
free(p);
q.length--;
return 1;
}

int visit(que &q,int e)
{
qtype p1,p2;
int i=0;
p2=q.front;
while((i+1)!=e)
{
i++;
p2=p2->next;
}
p1=p2->next;
p2->next=p1->next;
if(p2->next==q.rear) q.rear=p2;
free(p1);
q.length--;
}

int main()
{
int m,i,n,x,j,num;
char c[10];
que q;
QueInitial(q);
scanf("%d",&m);
for(i=1; i<=m; i++)
{
scanf("%d",&num);
InQue(q,num);
}
scanf("%d",&n);
while(n--)
{
scanf("%s",c);
if(strcmp(c,"JOIN")==0)
{
scanf("%d",&x);
InQue(q,x);
}
if(strcmp(c,"LEAVE")==0)
{
scanf("%d",&x);
visit(q,x);
}
if(strcmp(c,"FINISH")==0)
{
scanf("%d",&x);
for(i=0; i<x; i++)
{
DelQue(q);
}
}
if(strcmp(c,"LENGTH")==0)
{
printf("%d\n",q.length);
}
if(strcmp(c,"ASK")==0)
{
scanf("%d",&x);
qtype p;
p=q.front;
while(x--)
{
p=p->next;
}
printf("%d\n",p->data);
}
}
return 0;
}