使用c++实现一个银行家算法
时间: 2023-06-11 11:07:55 浏览: 45
银行家算法是一种避免系统死锁的算法,它通过动态地分配系统资源来避免进程之间的相互等待。下面是一个使用C语言实现银行家算法的示例代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define MAX_PROCESSES 10
#define MAX_RESOURCES 10
int available[MAX_RESOURCES];
int maximum[MAX_PROCESSES][MAX_RESOURCES];
int allocation[MAX_PROCESSES][MAX_RESOURCES];
int need[MAX_PROCESSES][MAX_RESOURCES];
bool finished[MAX_PROCESSES];
int num_processes, num_resources;
void input_data() {
printf("Enter the number of processes: ");
scanf("%d", &num_processes);
printf("Enter the number of resources: ");
scanf("%d", &num_resources);
printf("Enter the available resources: ");
for (int i = 0; i < num_resources; i++) {
scanf("%d", &available[i]);
}
printf("Enter the maximum needs of each process: ");
for (int i = 0; i < num_processes; i++) {
for (int j = 0; j < num_resources; j++) {
scanf("%d", &maximum[i][j]);
}
}
printf("Enter the resource allocation for each process: ");
for (int i = 0; i < num_processes; i++) {
for (int j = 0; j < num_resources; j++) {
scanf("%d", &allocation[i][j]);
need[i][j] = maximum[i][j] - allocation[i][j];
}
finished[i] = false;
}
}
bool is_safe(int process) {
for (int i = 0; i < num_resources; i++) {
if (need[process][i] > available[i]) {
return false;
}
}
return true;
}
void run_banker_algorithm() {
int safe_sequence[MAX_PROCESSES];
int num_finished = 0;
while (num_finished < num_processes) {
bool found = false;
for (int i = 0; i < num_processes; i++) {
if (!finished[i] && is_safe(i)) {
for (int j = 0; j < num_resources; j++) {
available[j] += allocation[i][j];
}
finished[i] = true;
safe_sequence[num_finished++] = i;
found = true;
}
}
if (!found) {
printf("System is in an unsafe state!\n");
exit(1);
}
}
printf("System is in a safe state.\nSafe sequence: ");
for (int i = 0; i < num_processes; i++) {
printf("%d ", safe_sequence[i]);
}
printf("\n");
}
int main() {
input_data();
run_banker_algorithm();
return 0;
}
```
这个程序会首先要求用户输入进程和资源的数量,以及每个进程的最大需求和当前已分配的资源数。然后,它会执行银行家算法来检查系统是否处于安全状态,并输出安全序列。如果系统处于不安全状态,程序会退出并输出错误消息。