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/*   实验以3.7.4为例  N=5个进程（p0,p1,p2,p3,p4) M=3类资源（A=10,B=5,C=7）  在T0时刻资源分配如下                     Max             Allocation           Need            Available                A    B    C       A     B     C       A    B     C      A    B      C    p0          7    5    3       0     1     0       7    4     3      3    3      2    p1          3    2    2       2     0     0       1    2     2    p2          9    0    2       3     0     2       6    0     0    p3          2    2    2       2     1     1       0    1     1    p4          4    3    3       0     0     2       4    3     1*/#include <iostream>using namespace std;#define N 5//进程数#define M 3//资源数int Available[M]={3,3,2};//可用资源向量//最大需求矩阵int Max[N][M]={ {7,5,3},{3,2,2},{9,0,2},{2,2,2},{4,3,3} };//分配矩阵int Allocation[N][M]={ {0,1,0},{2,0,0},{3,0,2},{2,1,1},{0,0,2}  };//需求矩阵int Need[N][M] = {  {7,4,3},{1,2,2},{6,0,0},{0,1,1},{4,3,1}  };//请求向量int Request[M];bool savety(int allocation[N][M],int need[N][M],int ava[M]);int check(int a,int request[]);void execute(int a,int request[M]);void print();void result(int res);int main(){    //安全性检测    int allocation[N][M];    int need[N][M];    int ava[M];    for(int i=0;i<M;i++) ava[i]=Available[i];    for(int i=0;i<N;i++){        for(int j=0;j<M;j++){            allocation[i][j]=Allocation[i][j];            need[i][j]=Need[i][j];        }    }    if(savety(allocation,need,ava))    {          cout<<"系统目前处于安全状态"<<endl<<endl;         //p1发出请求向量         Request[0]=1,Request[1]=0,Request[2]=2;         cout<<"P1发出请求向量Request(1,0,2)"<<endl;         int res=check(1,Request);         result(res);         cout<<endl<<endl;         //p4发出请求向量         Request[0]=3,Request[1]=3,Request[2]=0;         cout<<"P4发出请求向量Request(3,3,0)"<<endl;          res=check(4,Request);          result(res);          cout<<endl<<endl;          //p0发出请求向量          Request[0]=0,Request[1]=2,Request[2]=0;           cout<<"P0发出请求向量Request(0,2,0)"<<endl;          res=check(0,Request);          result(res);    }}//处理结果void result(int res){   if(res==1){            cout<<"系统是安全的,同意请求"<<endl;            //执行            execute(1,Request);            //打印            print();        }        else if(res==3)        {            cout<<"分配后系统是不安全的，拒绝请求!"<<endl;        }        else if(res==2)        {            cout<<"系统资源不足以分配，请等待"<<endl;        }}bool savety(int allocation[N][M],int need[N][M],int ava[M]){     int count=0;     int count2=0;     //安全序列   int SaveList[N]={-1,-1,-1,-1,-1};      cout<<"       Work       Need      Allocation      Work+Allocation    Finish"<<endl;      cout<<"    A   B   C   A   B   C    A   B   C       A   B   C"<<endl;     //虚拟分配     while(count<5&&count2<5){         for(int i=0;i<N;i++){        //排除已经执行完的进程        if(SaveList[0]==i)continue;        if(SaveList[1]==i)continue;        if(SaveList[2]==i)continue;        if(SaveList[3]==i)continue;        if(SaveList[4]==i)continue;        //寻找可以执行完毕的进程    if(need[i][0]<=ava[0]&&need[i][1]<=ava[1]&&need[i][2]<=ava[2]){        SaveList[count++]=i;        //回收资源        for(int j=0;j<M;j++)        ava[j]=ava[j]+allocation[i][j];        cout<<"p"<<i<<"  "<<ava[0]<<"   "<<ava[1]<<"   "<<ava[2]<<"   ";        cout<<need[i][0]<<"   "<<need[i][1]<<"   "<<need[i][2]<<"    ";        cout<<allocation[i][0]<<"   "<<allocation[i][1]<<"   "<<allocation[i][2]<<"       ";        cout<<ava[0]+allocation[i][0]<<"   "<<ava[1]+allocation[i][1]<<"   "<<ava[2]+allocation[i][2]<<"          true"<<endl;       }     }     count2++;  }  if(count==5){    cout<<"存在安全序列：";    for(int i=0;i<N;i++)        cout<<SaveList[i]<<"   ";        cout<<endl;        return true;  }  else  {      cout<<"不存在安全序列 "<<endl;    return false;  }}//a为线程号，request为请求表，返回结果：1.通过 2,等待  3.不通过int  check(int a,int request[]){    //检查是否小于需求    if(!(request[0]<=Need[a][0]&&request[1]<=Need[a][1]&&request[2]<=Need[a][2])){        return 3;    }    //检查是否小于可用资源    if(!(request[0]<=Available[0]&&request[1]<=Available[1]&&request[2]<=Available[2])){        return 2;    }    //试探分配    int ava[M];    for(int i=0;i<M;i++)ava[i]=Available[i];    int allocation[N][M];    int need[N][M];    for(int i=0;i<N;i++){        for(int j=0;j<M;j++){            allocation[i][j]=Allocation[i][j];            need[i][j]=Need[i][j];        }    }    //分配并修改    for(int i=0;i<M;i++){        ava[i]-=request[i];        need[a][i]-=request[i];        allocation[a][i]+=request[i];    }    //安全性检查    if(savety(allocation,need,ava))        return 1;    else        return 3;}//执行函数，a为修改进程号，request为请求表void execute(int a,int request[M]){    for(int i=0;i<M;i++){        Allocation[a][i]+=request[i];        Need[a][i]-=request[i];        Available[i]-=request[i];    }}void print(){    cout<<"执行后："<<endl;   cout<<"         MAX       Allocation     Need"<<endl;   cout<<"       A  B  C      A  B  C      A  B  C "<<endl;   for(int i=0;i<N;i++)   cout<<"p"<<i<<"     "<<Max[i][0]<<"  "<<Max[i][1]<<"  "<<Max[i][2]<<"      "<<Allocation[i][0]<<"  "<<Allocation[i][1]<<"  "<<Allocation[i][2]<<"      "<<Need[i][0]<<"  "<<Need[i][1]<<"  "<<Need[i][2]<<endl;    cout<<"Available:A("<<Available[0]<<")   B("<<Available[1]<<")    C("<<Available[2]<<")"<<endl;}