银行家算法模拟程序C语言

以下是一个简单的银行家算法模拟程序的C语言实现：

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

#define P 5 // 进程数
#define R 3 // 资源数

int available[R]; // 可用资源数
int max[P][R]; // 最大需求矩阵
int allocation[P][R]; // 已分配矩阵
int need[P][R]; // 需求矩阵
bool finish[P]; // 进程是否完成

void init() {
    // 初始化可用资源数
    available[0] = 3;
    available[1] = 3;
    available[2] = 2;

    // 初始化最大需求矩阵
    max[0][0] = 7;
    max[0][1] = 5;
    max[0][2] = 3;
    max[1][0] = 3;
    max[1][1] = 2;
    max[1][2] = 2;
    max[2][0] = 9;
    max[2][1] = 0;
    max[2][2] = 2;
    max[3][0] = 2;
    max[3][1] = 2;
    max[3][2] = 2;
    max[4][0] = 4;
    max[4][1] = 3;
    max[4][2] = 3;

    // 初始化已分配矩阵
    allocation[0][0] = 0;
    allocation[0][1] = 1;
    allocation[0][2] = 0;
    allocation[1][0] = 2;
    allocation[1][1] = 0;
    allocation[1][2] = 0;
    allocation[2][0] = 3;
    allocation[2][1] = 0;
    allocation[2][2] = 2;
    allocation[3][0] = 2;
    allocation[3][1] = 1;
    allocation[3][2] = 1;
    allocation[4][0] = 0;
    allocation[4][1] = 0;
    allocation[4][2] = 2;

    // 初始化需求矩阵
    for (int i = 0; i < P; i++) {
        for (int j = 0; j < R; j++) {
            need[i][j] = max[i][j] - allocation[i][j];
        }
    }

    // 初始化进程是否完成
    for (int i = 0; i < P; i++) {
        finish[i] = false;
    }
}

bool is_safe() {
    int work[R];
    for (int i = 0; i < R; i++) {
        work[i] = available[i];
    }

    bool finish_all = false;
    while (!finish_all) {
        bool can_alloc = false;
        for (int i = 0; i < P; i++) {
            if (!finish[i]) {
                bool can_finish = true;
                for (int j = 0; j < R; j++) {
                    if (need[i][j] > work[j]) {
                        can_finish = false;
                        break;
                    }
                }
                if (can_finish) {
                    can_alloc = true;
                    finish[i] = true;
                    for (int j = 0; j < R; j++) {
                        work[j] += allocation[i][j];
                    }
                }
            }
        }
        if (!can_alloc) {
            finish_all = true;
            for (int i = 0; i < P; i++) {
                if (!finish[i]) {
                    return false;
                }
            }
        }
    }
    return true;
}

void request(int pid, int request[R]) {
    bool can_alloc = true;
    for (int i = 0; i < R; i++) {
        if (request[i] > need[pid][i] || request[i] > available[i]) {
            can_alloc = false;
            break;
        }
    }
    if (can_alloc) {
        for (int i = 0; i < R; i++) {
            available[i] -= request[i];
            allocation[pid][i] += request[i];
            need[pid][i] -= request[i];
        }
        if (is_safe()) {
            printf("分配成功，安全序列为：");
            for (int i = 0; i < P; i++) {
                if (finish[i]) {
                    printf("%d ", i);
                }
            }
            printf("\n");
        } else {
            printf("分配失败，不安全状态\n");
            for (int i = 0; i < R; i++) {
                available[i] += request[i];
                allocation[pid][i] -= request[i];
                need[pid][i] += request[i];
            }
        }
    } else {
        printf("分配失败，请求资源超过需求或可用资源\n");
    }
}

void show() {
    printf("当前时刻各进程的资源分配情况：\n");
    printf("进程\t最大需求\t已分配\t\t需求\t\t可用资源\n");
    for (int i = 0; i < P; i++) {
        printf("%d\t", i);
        for (int j = 0; j < R; j++) {
            printf("%d ", max[i][j]);
        }
        printf("\t");
        for (int j = 0; j < R; j++) {
            printf("%d ", allocation[i][j]);
        }
        printf("\t\t");
        for (int j = 0; j < R; j++) {
            printf("%d ", need[i][j]);
        }
        printf("\t\t");
        if (i == 0) {
            printf("%d %d %d\n", available[0], available[1], available[2]);
        } else {
            printf("\n");
        }
    }
}

int main() {
    init();
    show();

    int pid;
    int request[R];
    while (true) {
        printf("请输入进程编号和请求资源数（格式：pid r1 r2 r3）：");
        scanf("%d %d %d %d", &pid, &request[0], &request[1], &request[2]);
        request(pid, request);
        show();
    }

    return 0;
}