#include <stdio.h>
    #include <stdlib.h>
    struct PCB
    {
       int pid;//程序識別符號
       int rr;//已執行時間
       int time;//程序要求執行時間
       char sta;//程序的狀態
       struct PCB *next;//連結指標
    };
    struct PCB pcb1,pcb2,pcb3,pcb4,pcb5,*tail,*head,*rp;
    void init()//初始化各個程序的執行時間
    {
       int time;
       pcb1.pid = 1;
       pcb2.pid = 2;
       pcb3.pid = 3;
       pcb4.pid = 4;
       pcb5.pid = 5;
       pcb1.rr =pcb2.rr =pcb3.rr =pcb4.rr =pcb5.rr = 0;
       pcb1.sta = pcb2.sta = pcb3.sta = pcb4.sta = pcb5.sta = 'w';
       printf("請輸入程序p1需要執行的時間:");
       scanf("%d",&time);
       pcb1.time =time;
       printf("請輸入程序p2需要執行的時間:");
       scanf("%d",&time);
       pcb2.time=time;
       printf("請輸入程序p3需要執行的時間:");
       scanf("%d",&time);
       pcb3.time=time;
       printf("請輸入程序p4需要執行的時間:");
       scanf("%d",&time);
       pcb4.time =time;
       printf("請輸入程序p5需要執行的時間:");
       scanf("%d",&time);
       pcb5.time=time;
       pcb1.next=&pcb2;
       pcb2.next=&pcb3;
       pcb3.next=&pcb4;
       pcb4.next=&pcb5;
       pcb5.next=&pcb1;
       head=&pcb1;
       tail=&pcb5;
    }
    void printf1()//顯示錶頭
    {
       printf("+---------------|---------------|---------------|---------------+\n");
       printf("|\tpid\t|\trr\t|\ttime\t|\tSTA\t|\n");
       printf("|---------------|---------------|---------------|---------------|\n");
    }
    void printf2()//顯示各個程序的初始狀態
    {
       printf("processes p%d running\n",head->pid);
       printf1();
       printf("|\t%d\t|\t%d\t|\t%d\t|\t%c\t|\n",head->pid,head->rr,head->time,head->sta);
       printf("|---------------|---------------|---------------|---------------|\n");
       rp=head;
       while(rp!=tail)
       {
          rp=rp->next;
          printf("|\t%d\t|\t%d\t|\t%d\t|\t%c\t|\n",rp->pid,rp->rr,rp->time,rp->sta);
          printf("|---------------|---------------|---------------|---------------|\n");
       }
    }
    void operation()//執行
    {
       int flag=1;
       while(flag<=5)
       {
          head->rr++;
          if((head->rr==head->time)||(head->time==0))
          {
             tail->sta='w';//將程序狀態設定為等待態
             head->sta='f';//將程序狀態設定為執行態
             printf2();
             head=head->next;
             tail->next=head;
             flag++;
          }
          else
          {
             tail->sta='w';//將程序狀態設定為等待態
             head->sta='r';//將程序狀態設定為就緒態
             printf2();
             tail=head;
             head=head->next;
          }
       }
    }
 void main()
    {
       init();
       printf2();
       operation();
    }