用c语言写一个银行家算法
时间: 2023-11-15 07:04:09 浏览: 26
银行家算法是一种资源分配算法,用于避免死锁。以下是一个简单的银行家算法的C语言实现:
```c
#include<stdio.h>
#define MAX_PROCESSES 10
#define MAX_RESOURCES 10
int available[MAX_RESOURCES];
int max[MAX_PROCESSES][MAX_RESOURCES];
int allocation[MAX_PROCESSES][MAX_RESOURCES];
int need[MAX_PROCESSES][MAX_RESOURCES];
int processes, resources;
void input()
{
int i, j;
printf("Enter the number of processes: ");
scanf("%d", &processes);
printf("Enter the number of resources: ");
scanf("%d", &resources);
printf("Enter the available resources: ");
for(i=0; i<resources; i++)
scanf("%d", &available[i]);
printf("Enter the maximum resources required by each process:\n");
for(i=0; i<processes; i++)
{
printf("For process %d: ", i+1);
for(j=0; j<resources; j++)
scanf("%d", &max[i][j]);
}
printf("Enter the resources allocated to each process:\n");
for(i=0; i<processes; i++)
{
printf("For process %d: ", i+1);
for(j=0; j<resources; j++)
{
scanf("%d", &allocation[i][j]);
need[i][j] = max[i][j] - allocation[i][j];
}
}
}
int banker(int process, int request[])
{
int i, j, k;
for(i=0; i<resources; i++)
{
if(request[i]>need[process][i])
return 0;
if(request[i]>available[i])
return 0;
}
for(i=0; i<resources; i++)
{
available[i] -= request[i];
allocation[process][i] += request[i];
need[process][i] -= request[i];
}
int safe_sequence[processes], count = 0;
int finish[processes];
for(i=0; i<processes; i++)
finish[i] = 0;
int work[resources];
for(i=0; i<resources; i++)
work[i] = available[i];
while(count<processes)
{
int found = 0;
for(i=0; i<processes; i++)
{
if(finish[i]==0)
{
int flag = 1;
for(j=0; j<resources; j++)
{
if(need[i][j]>work[j])
{
flag = 0;
break;
}
}
if(flag)
{
for(k=0; k<resources; k++)
work[k] += allocation[i][k];
finish[i] = 1;
safe_sequence[count++] = i;
found = 1;
}
}
}
if(!found)
break;
}
if(count<processes)
{
for(i=0; i<resources; i++)
{
available[i] += request[i];
allocation[process][i] -= request[i];
need[process][i] += request[i];
}
return 0;
}
printf("Safe sequence: ");
for(i=0; i<processes; i++)
printf("%d ", safe_sequence[i]+1);
printf("\n");
return 1;
}
int main()
{
input();
int process, i, request[MAX_RESOURCES];
while(1)
{
printf("Enter the process number (0 to exit): ");
scanf("%d", &process);
if(process==0)
break;
printf("Enter the resource request for process %d: ", process);
for(i=0; i<resources; i++)
scanf("%d", &request[i]);
if(banker(process-1, request))
printf("Request granted.\n");
else
printf("Request denied.\n");
}
return 0;
}
```
这个实现允许用户输入进程数、资源数、可用资源数量、每个进程的最大资源需求、每个进程已分配的资源,然后通过银行家算法来检查一个进程是否能够获得资源,以及在给定资源的情况下是否存在一种安全的执行顺序。
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