C Program for Optimal Page Replacement Algorithm

OUTPUT :
2 -1 -1
2 3 -1
2 3 -1
2 3 1
2 3 5
2 3 5
4 3 5
4 3 5
4 3 5
2 3 5
2 3 5
2 3 5

no of page faults : 3

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#include<stdio.h>
#include<conio.h>
   int fr[3];
      void main()
       {
	 void display();
	  int p[12]={2,3,2,1,5,2,4,5,3,2,5,2},i,j,fs[3];
	   int max,found=0,lg[3],index,k,l,flag1=0,flag2=0,pf=0,frsize=3;
	    clrscr();
	      for(i=0;i<3;i++)
	       {
		 fr[i]=-1;
	       }
		 for(j=0;j<12;j++)
	{
	   flag1=0;
	      flag2=0;
		for(i=0;i<3;i++)
	     {
		 if(fr[i]==p[j])
		  {
		    flag1=1;
		      flag2=1;
			     break;
		  }
	     }
	       if(flag1==0)
		{
		  for(i=0;i<3;i++)
		       {
			  if(fr[i]==-1)
				  {
				     fr[i]=p[j];
					flag2=1;
					   break;
				  }
			}
	       }
 
		 if(flag2==0)
		    {
		       for(i=0;i<3;i++)
			  lg[i]=0;
			      for(i=0;i<frsize;i++)
				       {
					  for(k=j+1;k<12;k++)
					       {
						  if(fr[i]==p[k])
						       {
							  lg[i]=k-j;
							      break;
						       }
				      }
			}
			  found=0;
			     for(i=0;i<frsize;i++)
				{
				   if(lg[i]==0)
					{
					 index=i;
					    found=1;
						break;
					  }
				  }
				    if(found==0)
					{
					  max=lg[0];
					     index=0;
						for(i=1;i<frsize;i++)
						   {
						     if(max<lg[i])
							{
							max=lg[i];
							 index=i;
					   }
			      }
		 }
	       fr[index]=p[j];
	       pf++;
	}
	   display();
}
	printf("\n no of page faults:%d",pf);
	       getch();
}
void display()
{
int i;
printf("\n");
for(i=0;i<3;i++)
printf("\t%d",fr[i]);
}

OUTPUT :
2 -1 -1
2 3 -1
2 3 -1
2 3 1
2 3 5
2 3 5
4 3 5
4 3 5
4 3 5
2 3 5
2 3 5
2 3 5

no of page faults : 3

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