银行家算法 C语言

银行家算法是一种避免死锁的算法，它通过动态地分配资源来避免进程死锁。下面是一个简单的C语言实现：

#include <stdio.h>
#include <stdbool.h>

// 定义最大进程数和资源数
#define MAX_PROCESS 10
#define MAX_RESOURCE 10

// 定义进程和资源的数量
int num_process, num_resource;

// 定义可用资源和最大需求矩阵
int available[MAX_RESOURCE], max_need[MAX_PROCESS][MAX_RESOURCE];

// 定义已分配和需求矩阵
int allocation[MAX_PROCESS][MAX_RESOURCE], need[MAX_PROCESS][MAX_RESOURCE];

// 定义安全序列
int safe_sequence[MAX_PROCESS];

// 检查进程是否可以分配资源
bool is_safe(int process) {
    // 检查进程的需求是否小于等于可用资源
    for (int i = 0; i < num_resource; i++) {
        if (need[process][i] > available[i]) {
            return false;
        }
    }
    return true;
}

// 银行家算法
bool banker_algorithm() {
    // 初始化工作
    int work[MAX_RESOURCE];
    for (int i = 0; i < num_resource; i++) {
        work[i] = available[i];
    }
    bool finish[MAX_PROCESS] = {false};

    // 找到一个安全序列
    int count = 0;
    while (count < num_process) {
        bool found = false;
        for (int i = 0; i < num_process; i++) {
            if (!finish[i] && is_safe(i)) {
                // 找到一个可以分配资源的进程
                for (int j = 0; j < num_resource; j++) {
                    work[j] += allocation[i][j];
                }
                safe_sequence[count++] = i;
                finish[i] = true;
                found = true;
            }
        }
        if (!found) {
            // 没有找到可以分配资源的进程
            return false;
        }
    }
    return true;
}

int main() {
    // 输入进程和资源的数量
    printf("Enter the number of processes: ");
    scanf("%d", &num_process);
    printf("Enter the number of resources: ");
    scanf("%d", &num_resource);

    // 输入可用资源和最大需求矩阵
    printf("Enter the available resources: ");
    for (int i = 0; i < num_resource; i++) {
        scanf("%d", &available[i]);
    }
    printf("Enter the maximum need matrix:\n");
    for (int i = 0; i < num_process; i++) {
        printf("Process %d: ", i);
        for (int j = 0; j < num_resource; j++) {
            scanf("%d", &max_need[i][j]);
        }
    }

    // 输入已分配矩阵并计算需求矩阵
    printf("Enter the allocation matrix:\n");
    for (int i = 0; i < num_process; i++) {
        printf("Process %d: ", i);
        for (int j = 0; j < num_resource; j++) {
            scanf("%d", &allocation[i][j]);
            need[i][j] = max_need[i][j] - allocation[i][j];
        }
    }

    // 运行银行家算法
    if (banker_algorithm()) {
        printf("Safe sequence: ");        for (int i = 0; i < num_process; i++) {
            printf("%d ", safe_sequence[i]);
        }
        printf("\n");
    } else {
        printf("Unsafe state\n");
    }

    return 0;
}