时间片轮转进程调度

#include <cstdio>
#include <cstdlib>
#define N 6
struct PCB
{
	int pid;			// 进程标识符
	int rr;				// 已运行时间
	int time;			// 进程要求运行时间
	char state;			// 进程的状态
	struct PCB * next;	// 链接指针 
};
struct PCB pcb[N];
struct PCB *tail, *head, *rp;

void init()
{
	int time;
	for(int i = 1; i < N; ++ i)
	{
		pcb[i].pid = i;
		pcb[i].rr = 0;
		pcb[i].state = 'w';
		printf("请输入进程p%d需要运行的时间:", i);
		scanf("%d", &pcb[i].time);
	}
	pcb[1].next = &pcb[2];
	pcb[2].next = &pcb[3];
	pcb[3].next = &pcb[4];
	pcb[4].next = &pcb[5];
	pcb[5].next = &pcb[1];
	head = &pcb[1];
	tail = &pcb[5];
	
}

// 显示表头 
void print1()
{
	printf("+---------------|---------------|---------------|---------------+\n");
	printf("|\tpid\t|\trr\t|\ttime\t|\tSTATE\t|\n");
	printf("|---------------|---------------|---------------|---------------|\n");
} 

// 显示各个进程的初始状态
void print2()
{
	printf("processes p %d running\n", head->pid);
	print1();
	printf("|\t%d\t|\t%d\t|\t%d\t|\t%c\t|\n", head->pid, head->rr, head->time, head->state);
	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->state);
		printf("|---------------|---------------|---------------|---------------|\n");
	}
} 

// 运行
void operation()
{
	int flag = 1;
	while(flag <= 5)
	{
		head->rr ++;
		if((head->rr == head->time) || (head->time == 0))
		{
			tail->state = 'w';		// 将进程状态设置为等待态
			head->state = 'f';		// 将进程状态设置为终止态 
			print2();
			head = head->next;
			tail->next = head;
			flag ++;
		}
		else
		{
			tail->state = 'w';		// 将进程状态设置为等待态
			head->state = 'r';		// 将进程状态设置为运行态
			print2();
			tail = head;
			head = head->next;
		}
	}
} 

int main()
{
	init();
	print2();
	operation();
	
	return 0;
}