srand()函数和rand()函数:
函数一:int rand(void);
功能:产生随机值,从srand (seed)中指定的seed开始,返回一个[seed, RAND_MAX(0x7fff))间的随机整数。
函数二:void srand(unsigned seed);
参数seed是rand()的种子,用来初始化rand()的起始值。
可以认为rand()在每次被调用的时候,它会查看:
1) 如果用户在此之前调用过srand(seed),给seed指定了一个值,那么它会自动调用srand(seed)一次来初始化它的起始值。
2) 如果用户在此之前没有调用过srand(seed),它会自动调用srand(1)一次
离散事件模拟
#include <stdio.h>
#include <stdlib.h>
#include<string.h>
#include<bits/stdc++.h>
#include <time.h>
#define OK 1
#define ERROR 0
#define TRUE 1
#define FALSE 0
using namespace std;
typedef int Status;
typedef struct Event { //事件类型
int OccurTime; //事件发生时刻
int NType; //事件类型,0表示到达事件,1至4表示四个窗口的离开事件
struct Event* next;
}Event, ElemType;
typedef struct { //单向链表结构
ElemType* head;//头指针
ElemType* tail;//尾指针
int len; //长度
}LinkList;
typedef LinkList EventList; //事件链表
typedef struct QElemType { //队列元素
int ArriveTime;//到达时间
int Duration;//办理业务所需时间
struct QElemType* next;
}QElemType;
typedef struct {//队列结构
QElemType* head;//头指针
QElemType* tail;//尾指针
}LinkQueue;
Event NewEvent(int occurT, int nType);
//根据OccurTime和NType值,创建新事件
Status InitList(LinkList* L);
//初始化事件链表
Status OrderInsert(LinkList* L, Event e);
//将事件e按发生时间顺序插入有序链表L中
Status ListEmpty(LinkList* L);
//判断链表L是否为空,为空返回TRUE,否则返回FALSE
Status DelFirst(LinkList* L, ElemType* e);
//链表L不为空,删除其首结点,用e返回,并返回OK;否则返回ERROR
Status ListTraverse(LinkList* L);
//遍历链表
Status InitQueue(LinkQueue* Q);
//初始化队列Q
Status EmptyQueue(LinkQueue* Q);
//若队列Q为空,返回TRUE,否则返回FALSE
Status DelQueue(LinkQueue* Q, QElemType* e);
//若队列Q不为空,首结点出队,用e返回,并返回OK;否则返回ERROR
Status EnQueue(LinkQueue* Q, QElemType e);
//结点e入队Q
int QueueLength(LinkQueue Q);
//返回队列Q的长度,即元素个数
Status GetHead(LinkQueue* Q, QElemType* e);
//若队列Q不为空,用e返回其首结点,并返回OK,否则返回ERROR
Status QueueTraverse(LinkQueue* Q);
//遍历队列Q
//------------------//
int Min(int a[], int n);
//返回长度为n的数组a第一个最小值的下标,从1开始
int ShortestQueue();
//获取最短队列的编号
void OpenForDay();
//初始化操作
void CustomerArrived();
//顾客达到事件
void CustomerDepature();
//顾客离开事件
void Bank_Simulation();
//银行排队模拟
void PrintEventList();
//输出事件队列
void PrintQueue();
//打印当前队列
EventList ev;
Event en;
LinkQueue q[5];
QElemType customer;
int TotalTime, CustomerNum;
int CloseTime = 50;//关闭时间,即营业时间长度
int main()
{
Bank_Simulation();
return 0;
}
void OpenForDay() {
//初始化操作
int i;
TotalTime = 0; CustomerNum = 0;
InitList(&ev);//初始化事件队列
en.OccurTime = 0;
en.NType = 0;
OrderInsert(&ev, en);
for (i = 1; i <= 4; i++)
InitQueue(&q[i]);//初始化四个窗口队列
}//OpenForDay
void CustomerArrived() {
//顾客达到事件
int durtime, intertime, i, t;
QElemType e;
++CustomerNum;
intertime = rand() % 5 + 1;//间隔时间在5分钟内
durtime = rand() % 30 + 1;//办理业务时间在30分钟内
t = en.OccurTime + intertime;
if (t < CloseTime) {//银行尚未关门
printf("A new customer will arrive at:%d\n", en.OccurTime);//下一位顾客达到时间
OrderInsert(&ev, NewEvent(t, 0));
i = ShortestQueue();//最短队列
e.ArriveTime = en.OccurTime;
e.Duration = durtime;
EnQueue(&q[i], e);
if (QueueLength(q[i]) == 1)
OrderInsert(&ev, NewEvent(en.OccurTime + durtime, i));
}
}
void CustomerDepature() {
//顾客离开事件
int i = en.NType;
DelQueue(&q[i], &customer);
printf("A customer leaves at:%d\n", en.OccurTime);//输出顾客离开时间
TotalTime += en.OccurTime - customer.ArriveTime;
if (!EmptyQueue(&q[i])) {
GetHead(&q[i], &customer);
OrderInsert(&ev, NewEvent(en.OccurTime + customer.Duration, i));
}
}
void Bank_Simulation() {
//银行排队模拟
OpenForDay();
srand((unsigned)time(NULL));//产生随机数列
while (!ListEmpty(&ev)) {
DelFirst(&ev, &en);
if (en.NType == 0)
CustomerArrived();
else
CustomerDepature();
//PrintEventList();
PrintQueue();
}
printf("\nTotal time is: %d min,average time is: %g min.\n", TotalTime, (float)TotalTime / CustomerNum);
}
void PrintQueue() {
//打印当前队列
int i;
for (i = 1; i <= 4; i++) {
printf("Queue %d have %d customer(s):", i, QueueLength(q[i]));
QueueTraverse(&q[i]);
}
printf("\n");
}
void PrintEventList() {
//输出事件队列
printf("Current Eventlist is:\n");
ListTraverse(&ev);
}
int Min(int a[], int n) {
//返回长度为n的数组a第一个最小值的下标,从0开始
int i, tmp, ind = 0;
tmp = a[0];
for (i = 1; i < n; i++) {
if (a[i] < tmp) {
tmp = a[i];
ind = i;
}
}
return ind;
}
int ShortestQueue() {
//获取最短队列的编号
int i, a[4];
for (i = 1; i <= 4; i++) {
a[i - 1] = QueueLength(q[i]);
//printf("队%d的长度为%d\n",i,QueueLength(q[i]));
}
return Min(a, 4) + 1;//队列从1开始编号
}
Event NewEvent(int occurT, int nType) {
//根据OccurTime和NType值,创建新事件
Event e;
e.OccurTime = occurT;
e.NType = nType;
return e;
}
Status InitList(LinkList* L) {
//初始化事件链表
L->head = L->tail = (ElemType*)malloc(sizeof(ElemType));
if (!L->head) {
printf("Apply for memory error.LinkList initialize failed.\n");
exit(0);
}
L->head->next = NULL;
return OK;
}
Status OrderInsert(LinkList* L, Event e) {
//将事件e按发生时间顺序插入有序链表L中
ElemType* p, * q, * newptr;
newptr = (ElemType*)malloc(sizeof(ElemType));
if (!newptr) {
printf("Apply for memory error,new node can't insert intot the Eventlist.\n");
exit(0);
}
*newptr = e;
if (TRUE == ListEmpty(L)) {//链表为空
L->head->next = newptr;
L->tail = newptr;
L->tail->next = NULL;
return OK;
}
q = L->head;
p = L->head->next;
while (p) {//遍历整个链表
if (p->OccurTime >= newptr->OccurTime)
break;
q = p;
p = p->next;
}
q->next = newptr;
newptr->next = p;
if (!p)//插入位置为链表尾部
L->tail = newptr;
return OK;
}
Status ListEmpty(LinkList* L) {
//判断链表L是否为空,为空返回TRUE,否则返回FALSE
if ((L->head == L->tail) && (L->head != NULL))
return TRUE;
else
return FALSE;
}
Status DelFirst(LinkList* L, ElemType* e) {
//链表L不为空,删除其首结点,用e返回,并返回OK;否则返回ERROR
ElemType* p = L->head->next;
if (!p)
return ERROR;
L->head->next = p->next;
*e = *p;
free(p);
if (L->head->next == NULL)
L->tail = L->head;
return OK;
}
Status ListTraverse(LinkList* L) {
//遍历链表
Event* p = L->head->next;
if (!p) {
printf("List is empty.\n");
return ERROR;
}
while (p != NULL) {
printf("OccurTime:%d,Event Type:%d\n", p->OccurTime, p->NType);
p = p->next;
}
printf("\n");
return OK;
}
Status InitQueue(LinkQueue* Q) {
//初始化队列Q
Q->head = Q->tail = (QElemType*)malloc(sizeof(QElemType));
if (!Q->head) {
printf("Apply for memory error.LinkQueue initialize failed.\n");
exit(0);
}
Q->head->next = NULL;
return OK;
}
Status EmptyQueue(LinkQueue* Q) {
//若队列Q为空,返回TRUE,否则返回FALSE
if (Q->head == Q->tail && Q->head != NULL)
return TRUE;
else
return FALSE;
}
Status DelQueue(LinkQueue* Q, QElemType* e) {
//若队列Q不为空,首结点出队,用e返回,并返回OK;否则返回ERROR
QElemType* p = Q->head->next;
if (!p)
return ERROR;
*e = *p;
Q->head->next = p->next;//修正队首指针
free(p);
if (!Q->head->next)//队空
Q->tail = Q->head;
return OK;
}
Status EnQueue(LinkQueue* Q, QElemType e) {
//结点e入队Q
QElemType* p = (QElemType*)malloc(sizeof(QElemType));
if (!p) {
printf("Apply for memory error,new element can't enqueue.\n");
exit(0);
}
*p = e;
p->next = NULL;
Q->tail->next = p;//插入队尾
Q->tail = p;//修改队尾指针
return OK;
}
int QueueLength(LinkQueue Q) {
//返回队列Q的长度,即元素个数
int count = 0;
QElemType* p = Q.head->next;
while (p) {
p = p->next;
count++;
}
return count;
}
Status GetHead(LinkQueue* Q, QElemType* e) {
//若队列Q不为空,用e返回其首结点,并返回OK,否则返回ERROR
if (EmptyQueue(Q))
return ERROR;
*e = *(Q->head->next);
return OK;
}
Status QueueTraverse(LinkQueue* Q) {
//遍历队列Q
QElemType* p = Q->head->next;
if (!p) {
printf("--Is empty.\n");
return ERROR;
}
while (p) {
printf("(%d,%d) ", p->ArriveTime, p->Duration);
p = p->next;
}
printf("\n");
return OK;
}