非抢占短作业优先算法源代码C语言

#include <stdio.h> #include <stdlib.h> #define MAX 5 //进程数

/*短作业优先算法*/ struct pro {

int num; //进程名 int arriveTime; //到达时间 int burst; //运行时间; struct pro *next; };

//函数声明

struct pro* creatList();

void insert(struct pro *head,struct pro *s); struct pro* searchByAT(struct pro *head,int AT); void run(struct pro *head); void del(struct pro* p);

int getCount(struct pro *head,int time);

struct pro* creatList() //创建链表，按照进程的到达时间排列 {

struct pro* head=(struct pro*)malloc(sizeof(struct pro)); head->next=NULL; struct pro* s; int i;

for(i=0;i<MAX;i++) {

s=(struct pro*)malloc(sizeof(struct pro)); printf("请输入进程名:\\n"); scanf("%d",&(s->num)); printf("请输入到达时间:\\n"); scanf("%d",&(s->arriveTime)); printf("请输入运行时间:\\n"); scanf("%d",&(s->burst)); s->next=NULL; insert(head,s);

}

return head; }

void insert(struct pro *head,struct pro *s) //插入节点 {

struct pro *p=searchByAT(head,s->arriveTime); s->next=p->next; p->next=s; return; }

struct pro* searchByAT(struct pro *head,int AT) //查找第一个到达时间大于等于AT的节点，返回其前一个指针 {

struct pro *p,*q; p=head; q=head->next;

while(q!=NULL&&q->arriveTime<=AT) { p=q; q=q->next; } return p; }

void del(struct pro* p) //删除p的下一个节点 {

struct pro *tmp; tmp=p->next; p->next=tmp->next; free(tmp); return; }

int getCount(struct pro *head,int time) //察看当前就绪队列中的进程数 {

int count=0; struct pro *p,*q; p=head; q=p->next;

while(q!=NULL&&q->arriveTime<=time) { count++;

p=q; q=q->next; }

return count; }

struct pro* SJF(struct pro *head,int count) //在头节点后的count个节点中选择burst最小的，返回其前一个节点的指针 { int min;

struct pro *p,*q,*flag; p=head; q=p->next; min=q->burst;

flag=p; //flag记录返回指针 while(count>0) {

if(q->burst<min) {

min=q->burst; flag=p; } count--; p=q; q=q->next; }

return flag; }

void run(struct pro *head) //按短作业优先算法调度进程，并输出其运行情况 {

int time=0,count; struct pro *s,*t;

while(head->next!=NULL) {

count=getCount(head,time);

if(count==0) //如果当前就绪队列中没有进程，时间自增 time++;

else if(count==1) //如果就绪队列中只有1个进程，则必定是第一个节点 { t=head; s=t->next;

printf("进程名:%d\\n",s->num); printf("到达时间:%d\\n",s->arriveTime);

printf("运行开始时间:%d\\n",time);

printf("响应时间:%d\\n",time-s->arriveTime); time+=s->burst;

printf("运行结束时间:%d\\n",time);

printf("周转时间:%d\\n",time-s->arriveTime); printf("*********************************\\n"); del(t

); }

else //如果就绪队列中的进程数>=2，则在head后的count个节点中进行短作业优先调度 {

t=SJF(head,count); s=t->next;

printf("进程名:%d\\n",s->num); printf("到达时间:%d\\n",s->arriveTime); printf("运行开始时间:%d\\n",time);

printf("响应时间:%d\\n",time-s->arriveTime); time+=s->burst;

printf("运行结束时间:%d\\n",time);

printf("周转时间:%d\\n",time-s->arriveTime); printf("*********************************\\n"); del(t); } } }

void main() {

struct pro *head=creatList();

printf("按短作业优先算法调度运行结果如下:\\n"); run(head);