C语言的超市模拟
Supermarket Simulation in C
我有一个看起来像这样的任务TASK1
我写了几行，我可以获得最大的客户市场，每个客户的到达时间和服务时间，但我不明白我应该如何跟踪时间和排队以获得问题 a) 和 b) 的答案。
我的代码是这样的
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
struct customer {
int serveTime;
int arriveTime;
} customer[1000];
int main()
{
srand( time(NULL) );
int randArrive, randServe, longestWait, currentQ, totalTime=0, i;
randArrive = rand() % 4 + 1;
customer[0].arriveTime = randArrive;
customer[0].serveTime = rand() % 4 + 1;
totalTime += randArrive;
currentQ = 1;
for ( i=1; totalTime<720; i++ )
{
customer[i].arriveTime = rand() % 4 + 1;
customer[i].serveTime = rand() % 4 + 1;
if ( customer[i].arriveTime < customer[i-1].serveTime )
totalTime += customer[i-1].serveTime;
else
totalTime += customer[i].arriveTime;
}
printf( "%d,%d", totalTime, i );
return 0;
}
P.S.: 作为学生的编码新手，每条提示都会有所帮助，谢谢。
下面是我解决任务的代码。
请注意，我并没有严格遵循任务中描述的算法。根据任务，当前正在服务的客户不应该是队列的一部分，但应该在服务之前出队。但是，我发现如果您将当前正在接受服务的客户视为队列开头的客户，那么编程会更容易。
该任务还要求您将最大到达时间从 4 更改为 3 并观察变化。由于我在中心位置定义了值 4，因此您只需更改行
#define MAX_MINUTES_PER_ARRIVAL 4
以下内容：
#define MAX_MINUTES_PER_ARRIVAL 3
之后代码中两处的值4都会自动变为3
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// This header is only required in order to use the assert macro used below,
// but both this header and the assert macros are only used for debugging
// purposes and can be removed.
#include <assert.h>
// Instead of writing the value 720 in several places in the program, it is
// usually better to define the number in one place, so it can more easily be
// changed.
#define NUM_MINUTES 720
// Also, if the minimum and maximum random waiting times are defined in one
// central place, they are also easier to change, which actually must be done
// as part of the task.
#define MIN_MINUTES_PER_ARRIVAL 1
#define MAX_MINUTES_PER_ARRIVAL 4
#define MIN_MINUTES_PER_SERVICE 1
#define MAX_MINUTES_PER_SERVICE 4
// Since no more than one customer can arrive per minute, there can be no more
// than NUM_MINUTES customers, so this array is guaranteed to be large enough.
// If you want to save memory, you can use a linked list and dynamic memory
// allocation instead, but that may be slower.
static int customerArrivalTimes[NUM_MINUTES];
int main()
{
// This will seed the random number generator.
unsigned int seed = (unsigned)time( NULL );
printf( "seeding with %u\n", seed );
srand( seed );
// This variable always holds the time the next customer will arrive.
int nextArrival;
// This variable holds the time the cashier will finish serving the current
// customer. The value of -1 is reserved to indicate that no customer is
// currently being serviced.
int nextService = -1;
// This variable keeps record of the maximum waiting time a single customer
// experienced.
int longestWait = 0;
// This variable keeps track of the longest Queue Size ever encountered.
int longestQueue = 0;
// This variable specifies the current length of the queue.
int queueLength = 0;
// When queueLength == 0, queueStart specifies the index into the array
// customerArrivalTimes which will hold the next customer that arrives, so
// in that case it should be identical to the value of queueEnd.
// When queueLength != 0, queueStart specifies the index into the array
// customerArrivalTimes of the customer which is currently being serviced.
int queueStart = 0;
// When queueLength == 0, queueEnd specifies the index into the array
// customerArrivalTimes which will hold the next customer that arrives, so
// in that case it should be identical to the value of queueStart.
// When queueLength != 0, queueEnd specifies the index into the array
// customerArrivalTimes which will hold the next arriving customer (i.e.
// one beyond the last customer in the queue).
int queueEnd = 0;
// This will use the random number generator to set the arrival time of
// the first customer.
nextArrival = rand() % (MAX_MINUTES_PER_ARRIVAL + 1 - MIN_MINUTES_PER_ARRIVAL) + MIN_MINUTES_PER_ARRIVAL;
// This simulation will start at minute 0 and end at minute NUM_MINUTES - 1
for ( int i = 0; i < NUM_MINUTES; i++ )
{
//check if the next customer is scheduled to arrive in this minute
if ( nextArrival == i )
{
//update queueLength and test if record has been broken
queueLength++;
if ( queueLength > longestQueue ) longestQueue = queueLength;
//print information message
printf( "%03d:New customer arriving, queue length now: %d.\n", i, queueLength );
//remember the arrival time of the current customer
customerArrivalTimes[queueEnd++] = i;
//set random arrival time for next customer
nextArrival = rand() % (MAX_MINUTES_PER_ARRIVAL + 1 - MIN_MINUTES_PER_ARRIVAL) + MIN_MINUTES_PER_ARRIVAL + i;
//if queue was empty, start servicing the new customer
if ( queueLength == 1 )
{
// The following line will abort the program with an error
// message if nextService is a valid time value (not -1).
// This should not happen if the queue was empty. Therefore,
// this would indicate a bug in the program.
assert( nextService == -1 );
//schedule completion time of next customer service
nextService = rand() % (MAX_MINUTES_PER_SERVICE + 1 - MIN_MINUTES_PER_SERVICE) + MIN_MINUTES_PER_SERVICE + i;
}
}
//check if customer service is scheduled to finish in this minute
if ( nextService == i )
{
//print information message
printf(
"%03d:Customer service completed, total time: %d.\n",
i, i - customerArrivalTimes[queueStart]
);
// This code block will update the variable longestWait if the
// record was broken
if ( longestWait < i - customerArrivalTimes[queueStart] )
{
longestWait = i - customerArrivalTimes[queueStart];
}
//update the starting point and length of the queue
queueStart++;
queueLength--;
// The following line will abort the program with an error message
// if queueLength ever becomes negative (which should never happen
// and would indicate a bug in the program).
assert( queueLength >= 0 );
//if queue is not empty, start servicing the next customer
if ( queueLength != 0 )
{
//schedule completion time of next customer service
nextService = rand() % (MAX_MINUTES_PER_SERVICE + 1 - MIN_MINUTES_PER_SERVICE) + MIN_MINUTES_PER_SERVICE + i;
}
//otherwise indicate that no customer is currently being serviced
else
{
nextService = -1;
}
}
}
// This will print the longest total waiting time a customer experienced.
// This includes the waiting time for a customer to finish being serviced
// by the cashier, although the task description does not clearly specify
// whether this should be the case. Also, this does not take into account
// whether customers still waiting in the queue when the store closes
// will or already have had a longer waiting time, as the task does not
// specify how these customers should be handled.
printf( "Longest wait: %d\n", longestWait );
// This will print the maximum queue length that was encountered.
printf( "Longest queue: %d\n", longestQueue );
return 0;
}
我有一个看起来像这样的任务TASK1
我写了几行，我可以获得最大的客户市场，每个客户的到达时间和服务时间，但我不明白我应该如何跟踪时间和排队以获得问题 a) 和 b) 的答案。 我的代码是这样的
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
struct customer {
int serveTime;
int arriveTime;
} customer[1000];
int main()
{
srand( time(NULL) );
int randArrive, randServe, longestWait, currentQ, totalTime=0, i;
randArrive = rand() % 4 + 1;
customer[0].arriveTime = randArrive;
customer[0].serveTime = rand() % 4 + 1;
totalTime += randArrive;
currentQ = 1;
for ( i=1; totalTime<720; i++ )
{
customer[i].arriveTime = rand() % 4 + 1;
customer[i].serveTime = rand() % 4 + 1;
if ( customer[i].arriveTime < customer[i-1].serveTime )
totalTime += customer[i-1].serveTime;
else
totalTime += customer[i].arriveTime;
}
printf( "%d,%d", totalTime, i );
return 0;
}
P.S.: 作为学生的编码新手，每条提示都会有所帮助，谢谢。
下面是我解决任务的代码。
请注意，我并没有严格遵循任务中描述的算法。根据任务，当前正在服务的客户不应该是队列的一部分，但应该在服务之前出队。但是，我发现如果您将当前正在接受服务的客户视为队列开头的客户，那么编程会更容易。
该任务还要求您将最大到达时间从 4 更改为 3 并观察变化。由于我在中心位置定义了值 4，因此您只需更改行
#define MAX_MINUTES_PER_ARRIVAL 4
以下内容：
#define MAX_MINUTES_PER_ARRIVAL 3
之后代码中两处的值4都会自动变为3
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// This header is only required in order to use the assert macro used below,
// but both this header and the assert macros are only used for debugging
// purposes and can be removed.
#include <assert.h>
// Instead of writing the value 720 in several places in the program, it is
// usually better to define the number in one place, so it can more easily be
// changed.
#define NUM_MINUTES 720
// Also, if the minimum and maximum random waiting times are defined in one
// central place, they are also easier to change, which actually must be done
// as part of the task.
#define MIN_MINUTES_PER_ARRIVAL 1
#define MAX_MINUTES_PER_ARRIVAL 4
#define MIN_MINUTES_PER_SERVICE 1
#define MAX_MINUTES_PER_SERVICE 4
// Since no more than one customer can arrive per minute, there can be no more
// than NUM_MINUTES customers, so this array is guaranteed to be large enough.
// If you want to save memory, you can use a linked list and dynamic memory
// allocation instead, but that may be slower.
static int customerArrivalTimes[NUM_MINUTES];
int main()
{
// This will seed the random number generator.
unsigned int seed = (unsigned)time( NULL );
printf( "seeding with %u\n", seed );
srand( seed );
// This variable always holds the time the next customer will arrive.
int nextArrival;
// This variable holds the time the cashier will finish serving the current
// customer. The value of -1 is reserved to indicate that no customer is
// currently being serviced.
int nextService = -1;
// This variable keeps record of the maximum waiting time a single customer
// experienced.
int longestWait = 0;
// This variable keeps track of the longest Queue Size ever encountered.
int longestQueue = 0;
// This variable specifies the current length of the queue.
int queueLength = 0;
// When queueLength == 0, queueStart specifies the index into the array
// customerArrivalTimes which will hold the next customer that arrives, so
// in that case it should be identical to the value of queueEnd.
// When queueLength != 0, queueStart specifies the index into the array
// customerArrivalTimes of the customer which is currently being serviced.
int queueStart = 0;
// When queueLength == 0, queueEnd specifies the index into the array
// customerArrivalTimes which will hold the next customer that arrives, so
// in that case it should be identical to the value of queueStart.
// When queueLength != 0, queueEnd specifies the index into the array
// customerArrivalTimes which will hold the next arriving customer (i.e.
// one beyond the last customer in the queue).
int queueEnd = 0;
// This will use the random number generator to set the arrival time of
// the first customer.
nextArrival = rand() % (MAX_MINUTES_PER_ARRIVAL + 1 - MIN_MINUTES_PER_ARRIVAL) + MIN_MINUTES_PER_ARRIVAL;
// This simulation will start at minute 0 and end at minute NUM_MINUTES - 1
for ( int i = 0; i < NUM_MINUTES; i++ )
{
//check if the next customer is scheduled to arrive in this minute
if ( nextArrival == i )
{
//update queueLength and test if record has been broken
queueLength++;
if ( queueLength > longestQueue ) longestQueue = queueLength;
//print information message
printf( "%03d:New customer arriving, queue length now: %d.\n", i, queueLength );
//remember the arrival time of the current customer
customerArrivalTimes[queueEnd++] = i;
//set random arrival time for next customer
nextArrival = rand() % (MAX_MINUTES_PER_ARRIVAL + 1 - MIN_MINUTES_PER_ARRIVAL) + MIN_MINUTES_PER_ARRIVAL + i;
//if queue was empty, start servicing the new customer
if ( queueLength == 1 )
{
// The following line will abort the program with an error
// message if nextService is a valid time value (not -1).
// This should not happen if the queue was empty. Therefore,
// this would indicate a bug in the program.
assert( nextService == -1 );
//schedule completion time of next customer service
nextService = rand() % (MAX_MINUTES_PER_SERVICE + 1 - MIN_MINUTES_PER_SERVICE) + MIN_MINUTES_PER_SERVICE + i;
}
}
//check if customer service is scheduled to finish in this minute
if ( nextService == i )
{
//print information message
printf(
"%03d:Customer service completed, total time: %d.\n",
i, i - customerArrivalTimes[queueStart]
);
// This code block will update the variable longestWait if the
// record was broken
if ( longestWait < i - customerArrivalTimes[queueStart] )
{
longestWait = i - customerArrivalTimes[queueStart];
}
//update the starting point and length of the queue
queueStart++;
queueLength--;
// The following line will abort the program with an error message
// if queueLength ever becomes negative (which should never happen
// and would indicate a bug in the program).
assert( queueLength >= 0 );
//if queue is not empty, start servicing the next customer
if ( queueLength != 0 )
{
//schedule completion time of next customer service
nextService = rand() % (MAX_MINUTES_PER_SERVICE + 1 - MIN_MINUTES_PER_SERVICE) + MIN_MINUTES_PER_SERVICE + i;
}
//otherwise indicate that no customer is currently being serviced
else
{
nextService = -1;
}
}
}
// This will print the longest total waiting time a customer experienced.
// This includes the waiting time for a customer to finish being serviced
// by the cashier, although the task description does not clearly specify
// whether this should be the case. Also, this does not take into account
// whether customers still waiting in the queue when the store closes
// will or already have had a longer waiting time, as the task does not
// specify how these customers should be handled.
printf( "Longest wait: %d\n", longestWait );
// This will print the maximum queue length that was encountered.
printf( "Longest queue: %d\n", longestQueue );
return 0;
}