银行家算法的C++实现 - 计算机操作系统

#include<iostream>
#define MAX 100
using namespace std;
int totalResource,totalProcess;
int Max[MAX][MAX]; // 最大需求矩阵max
int Allocation[MAX][MAX]; // 分配矩阵
int Need[MAX][MAX]; // 最多还需要资源矩阵
int Available[MAX]; // 可用资源向量

void inputMaxMartix() {
    cout << "请输入Max矩阵的数据：" << endl;
    for(int i=0; i<totalProcess; i++) {
        for(int j=0; j<totalResource; j++) {
            cin >> Max[i][j];
        }
    }
}

void inputAllocationMartix() {
    cout << "请输入Allocation矩阵的数据：" << endl;
    for(int i=0; i<totalProcess; i++) {
        for(int j=0; j<totalResource; j++) {
            cin >> Allocation[i][j];
        }
    }
}
void inputAvailable() {
    cout << "请输入Available资源向量" << endl;
    for(int i=0; i<totalResource; i++) {
        cin >> Available[i];
    }
}
// 通过Max矩阵和Allocation矩阵的数据来计算Need矩阵
void calculateNeed() {
    for(int i=0; i<totalProcess; i++) {
        for(int j=0; j<totalResource; j++) {
            Need[i][j]=Max[i][j]-Allocation[i][j];
        }
    }
}
// 输出当前数据
void print() {
    cout << "当前资源分配情况：" << endl;
    cout << "进程ID" <<  "\t\t" << "Max" <<  "\t\t" << "Allocation" <<  "\t\t" << "Need" << endl;
    for(int i=0; i<totalProcess; i++) {
        cout << i <<  "\t\t\t";
        for(int j=0; j<totalResource; j++) {
            cout << Max[i][j] << " ";
        }
        cout <<  "\t\t\t";
        for(int j=0; j<totalResource; j++) {
            cout << Allocation[i][j] << " ";
        }
        cout <<  "\t\t\t";
        for(int j=0; j<totalResource; j++) {
            cout << Need[i][j] << " ";
        }
        cout << endl;
    }
    cout << "各类资源可用数量：" << endl;
    for(int i=0; i<totalResource; i++) {
        cout << Available[i] << " ";
    }
    cout << endl;
}

//安全性检查函数 
bool check() {
    int safeSeq[totalProcess];
    int work[totalResource];
    int count = 0; // 安全序列Cursor;
    bool finish[totalProcess];
    for(int i=0; i<totalProcess; i++) {
        safeSeq[i] = 0;
        finish[i] = false;
    }

    for(int i=0; i<totalResource; i++) {
        work[i] = Available[i];
    }
    int unfinished = totalProcess;
    bool flag;
    do {
        for(int i=0; i<totalProcess; i++) {
            if(finish[i] == false) {
                flag = true;
                for(int j=0; j<totalResource; j++) {
                    if(Need[i][j] > work[j]) {
                        flag = false;
                        break;
                    }
                }
                if(flag) {
                    finish[i] = true;
                    safeSeq[count++] = i;
                    for(int j=0; j<totalResource; j++) {
                        work[j] += Allocation[i][j];
                    }
                }
            }

        }
        unfinished--;

    } while(unfinished>0);
    flag = true;
    // 判断是否所有进程都完成
    for(int i=0; i<totalProcess; i++) {
        if(finish[i]==false) {
            flag=false;
            break;
        }
    }
    // 判断是否安全
    if(flag==false) {
        cout << "系统处于不安全状态！" << endl;
    } else {
        cout << "系统当前为安全状态，安全序列为：" << endl;
        for(int i=0; i<totalProcess; i++) {
            cout << safeSeq[i] << " ";
        }
        cout << endl;
    }
    return flag;
}

void handleRequest() {
    int requestPid;
    int request[totalResource];
    int snapShotOfAvailable[totalResource];
    int snapShotOfAllocation[totalResource];
    int snapShotOfNeed[totalResource];

    cout << "请输入请求资源的ID：" << endl;
    cin >> requestPid;
    cout << "请输入请求向量Request：" << endl;
    for(int i=0; i<totalResource; i++) {
        cin >> request[i];
    }
    for(int i=0; i<totalResource; i++) {
        if(request[i] > Need[requestPid][i]) {
            cout << "请求资源数大于需要数量，分配失败" <<endl;
            return;
        }
        if(request[i] > Available[i]) {
            cout << "可用资源不足，分配失败" << endl;
            return;
        }
    }

    // 尝试分配
    for(int i=0; i<totalResource; i++) {
        //保存快照
        snapShotOfAvailable[i] = Available[i];
        snapShotOfAllocation[i] = Allocation[requestPid][i];
        snapShotOfNeed[i] = Need[requestPid][i];
        // 进行尝试分配
        Available[i] -= request[i];
        Allocation[requestPid][i] += request[i];
        Need[requestPid][i] -= request[i];
    }
    // 打印当前资源情况
    print();
    if(check() == false) { // 不安全，返回分配
        // 恢复快照
        for(int i=0; i<totalResource; i++) {
            // 进行尝试分配
            Available[i] = snapShotOfAvailable[i];
            Allocation[requestPid][i] = snapShotOfAllocation[i];
            Need[requestPid][i] -= snapShotOfNeed[i];
        }
    }

}
int main() {
    cout << "请输入进程数量：" << endl;
    cin >> totalProcess;
    cout << "请输入资源种类数量：" << endl;
    cin >> totalResource;

    inputMaxMartix();
    inputAllocationMartix();
    inputAvailable();
    calculateNeed();
    print();
    check();
    while(true){
        char signal;
        handleRequest();
        cout << "输入Y继续，输入N退出" << endl;
        cin >>  signal;
        if(signal == 'N'){
            return 0;
        }
    }
}