用c语言实现银行家算法

银行家算法是一种避免死锁的算法，主要用于计算机操作系统中进程的资源分配，以下是用C语言实现银行家算法的代码：

#include <stdio.h>
#define MAX_PROCESS 10
#define MAX_RESOURCE 10

int available[MAX_RESOURCE];
int max_demand[MAX_PROCESS][MAX_RESOURCE];
int allocated[MAX_PROCESS][MAX_RESOURCE];
int need[MAX_PROCESS][MAX_RESOURCE];
int safe_sequence[MAX_PROCESS];
int num_processes, num_resources;

int is_safe()
{
    int work[MAX_RESOURCE];
    int finish[MAX_PROCESS];
    int i, j, k, num_finished = 0;

    for(i = 0; i < num_resources; ++i)
        work[i] = available[i];

    for(i = 0; i < num_processes; ++i)
        finish[i] = 0;

    while(num_finished < num_processes)
    {
        int can_allocate = 0;

        for(i = 0; i < num_processes; ++i)
        {
            if(!finish[i])
            {
                can_allocate = 1;

                for(j = 0; j < num_resources; ++j)
                {
                    if(need[i][j] > work[j])
                    {
                        can_allocate = 0;
                        break;
                    }
                }

                if(can_allocate)
                {
                    for(k = 0; k < num_resources; ++k)
                        work[k] += allocated[i][k];

                    finish[i] = 1;
                    safe_sequence[num_finished] = i;
                    ++num_finished;
                }
            }
        }

        if(!can_allocate)
            break;
    }

    return num_finished == num_processes;
}

int main()
{
    int i, j;

    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(i = 0; i < num_resources; ++i)
        scanf("%d", &available[i]);

    printf("Enter the maximum demand of each process: ");
    for(i = 0; i < num_processes; ++i)
        for(j = 0; j < num_resources; ++j)
            scanf("%d", &max_demand[i][j]);

    printf("Enter the allocated resources of each process: ");
    for(i = 0; i < num_processes; ++i)
        for(j = 0; j < num_resources; ++j)
            scanf("%d", &allocated[i][j]);

    for(i = 0; i < num_processes; ++i)
        for(j = 0; j < num_resources; ++j)
            need[i][j] = max_demand[i][j] - allocated[i][j];

    if(is_safe())
    {
        printf("Safe sequence: ");
        for(i = 0; i < num_processes; ++i)
            printf("%d ", safe_sequence[i]);
        printf("\n");
    }
    else
        printf("Unsafe state\n");

    return 0;
}

代码中包含了一个`is_safe()`函数，用于检测系统是否处于安全状态。如果是安全状态，函数返回1，同时将安全序列存储在`safe_sequence`数组中；否则返回0。

在主函数中，首先读入系统的资源数、进程数、可用资源数量、各进程最大需求量和分配量，然后计算出各进程还需要的资源数量，并调用`is_safe()`函数检测系统是否处于安全状态。如果是安全状态，则输出安全序列；否则输出“Unsafe state”。