c语言编写银行家算法程序

银行家算法是一种避免死锁的算法，它可以用来分配资源并且避免进程因为竞争资源而无限期地等待。

下面是一个简单的C语言实现银行家算法的程序：

#include <stdio.h>
#include <stdbool.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];
bool finished[MAX_PROCESSES];

// 初始化数据
void init() {
    int i, j;
    printf("Enter the number of resources: ");
    int numResources;
    scanf("%d", &numResources);

    printf("Enter the number of processes: ");
    int numProcesses;
    scanf("%d", &numProcesses);

    printf("Enter the number of available resources: ");
    for (i = 0; i < numResources; i++) {
        scanf("%d", &available[i]);
    }

    printf("Enter the maximum resource allocation for each process:\n");
    for (i = 0; i < numProcesses; i++) {
        printf("Process %d: ", i + 1);
        for (j = 0; j < numResources; j++) {
            scanf("%d", &max[i][j]);
        }
    }

    printf("Enter the resource allocation for each process:\n");
    for (i = 0; i < numProcesses; i++) {
        printf("Process %d: ", i + 1);
        for (j = 0; j < numResources; j++) {
            scanf("%d", &allocation[i][j]);
            need[i][j] = max[i][j] - allocation[i][j];
        }
        finished[i] = false;
    }
}

// 查找一个未完成的进程
int findUnfinishedProcess(int numProcesses) {
    int i;
    for (i = 0; i < numProcesses; i++) {
        if (!finished[i]) {
            return i;
        }
    }
    return -1;
}

// 检查当前状态是否安全
bool isSafeState(int numProcesses, int numResources) {
    int work[MAX_RESOURCES];
    int i, j;
    for (i = 0; i < numResources; i++) {
        work[i] = available[i];
    }

    bool found;
    int unfinishedProcess = findUnfinishedProcess(numProcesses);
    while (unfinishedProcess >= 0) {
        found = true;
        for (j = 0; j < numResources; j++) {
            if (need[unfinishedProcess][j] > work[j]) {
                found = false;
                break;
            }
        }
        if (found) {
            for (j = 0; j < numResources; j++) {
                work[j] += allocation[unfinishedProcess][j];
            }
            finished[unfinishedProcess] = true;
        }
        unfinishedProcess = findUnfinishedProcess(numProcesses);
    }

    for (i = 0; i < numProcesses; i++) {
        if (!finished[i]) {
            return false;
        }
    }
    return true;
}

// 分配资源
bool allocateResources(int process, int numResources, int request[]) {
    int i;
    for (i = 0; i < numResources; i++) {
        if (request[i] > need[process][i] || request[i] > available[i]) {
            return false;
        }
    }
    for (i = 0; i < numResources; i++) {
        available[i] -= request[i];
        allocation[process][i] += request[i];
        need[process][i] -= request[i];
    }
    return true;
}

int main() {
    init();

    int numResources, numProcesses;
    printf("Enter the number of resources: ");
    scanf("%d", &numResources);
    printf("Enter the number of processes: ");
    scanf("%d", &numProcesses);

    int request[MAX_RESOURCES];
    int process;
    while (true) {
        printf("Enter the process number (0 to exit): ");
        scanf("%d", &process);
        if (process == 0) {
            break;
        }
        printf("Enter the resource request: ");
        int i;
        for (i = 0; i < numResources; i++) {
            scanf("%d", &request[i]);
        }
        if (allocateResources(process - 1, numResources, request)) {
            if (isSafeState(numProcesses, numResources)) {
                printf("Resource allocated successfully.\n");
            } else {
                printf("Resource allocation failed. Unsafe state detected.\n");
                allocateResources(process - 1, numResources, request);
            }
        } else {
            printf("Resource allocation failed. Requested resources exceed need or available resources.\n");
        }
    }

    return 0;
}

这个程序会首先要求用户输入资源数量、进程数量以及可用资源数量。然后，程序会要求用户输入每个进程的最大资源分配和当前资源分配。接下来，程序会提示用户输入要请求资源的进程和请求的资源数量。如果请求成功，程序会检查当前状态是否安全，如果是则分配资源，否则请求会被拒绝。

注意，这个程序假定用户输入是正确的。在实际使用中，需要对用户输入进行验证和错误处理。