hxl.c

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#include<stdio.h>
#define n 5
#define m 3


int available[m]={2,3,3},alloc[n][m]={{2,1,2},{4,0,2},{3,0,5},{2,0,4},{3,1,4}},
need[n][m]={{3,4,7},{1,3,4},{0,0,3},{2,2,1},{1,1,0}};

int safe()
{
	int finish[n]={0},j=0,i,k,g;
	 while(1)
	 {
         g=0;  
	    for(j=0;j<n;j++)
     {
         if(finish[j]==0)
         {
		    
			for(i=0,k=0;i<m;i++)
			 if(!(available[i]>=need[j][i])){k=1;break;}
			if(k==0)
			{
              finish[j]=1;
              
			  for(i=0;i<m;i++)available[i]=available[i]+alloc[j][i];
                            
			  g=1;
            }
         }
         if(g)break; 
     }  
        
       if(!g)break; 
	 }
		 
     for(i=0;i<n;i++)
	 {
		 if(finish[i])continue;
		 else return 0;
			 
        
    }	 
	 return 1;
	 
 }
 
 int input(int request[],int*q)
 {
	 int i;
	 scanf("%d",q);
	 for(i=0;i<m;i++) scanf("%d",&request[i]);
     return 0;
 }

main ()
{
	int request[m],q,i=0,k;
	while(1)
	{
		input(request,&q);
		if(q<=0)break;
        q--;
        k=1;
		for(i=0;i<m;i++)
		{
			if(!(request[i]<=need[q][i]))
		   
			{
				printf("这个是非法请求\n");
		
				k=0;
				break;
				
			}
			
		   if(!(request[i]<=available[i]))
			
			{
				printf("P%d阻塞\n",q);
				k=0;
				break;
				
			}
		}
		if(k==0)continue;
		for(i=0;i<m;i++)
		{
			available[i]=available[i] - request[i];
			alloc[q][i]=alloc[q][i]+request[i];       
			need[q][i]=need[q][i]-request[i];
		}
		if(safe()==1)
		{
			printf("这个请求是安全的\n");
			continue;
		}
		else
		{
			printf("这个请求不安全\n");
			for(i=0;i<m;i++)
			{
			available[i]=available[i] + request[i];
			alloc[q][i]=alloc[q][i]-request[i];       
			need[q][i]=need[q][i]+request[i];
			}
		}
	}
  printf("请求结束\n"); 
}