program for LRU page replacement algorithm .

#include<iostream.h>

#include<conio.h>

void main()

{

clrscr();

int q[20],p[50],c=0,c1,d,f,i,j,k=0,n,r,t,b[20],c2[20];

cout<<"Enter no of pages:";

cin>>n;

cout<<"Enter the reference string:";

for(i=0;i<n;i++)

cin>>p[i];

cout<<"Enter no of frames:";

cin>>f ;

q[k]=p[k];

cout<<"\n "<<q[k]<<"\n";

c++;

k++;

for(i=1;i<n;i++)

{

c1=0;

 for(j=0;j<f;j++)

{

 if(p[i]!=q[j])

c1++;

}

if(c1==f)

c++;

if(k<f)

{

q[k]=p[i];

k++;

for(j=0;j<k;j++)

cout<<" "<<q[j];

cout<<"\n";

}

else

{

for(r=0;r<f;r++)

{

c2[r]=0;

for(j=i-1;j<n;j--)

{

if(q[r]!=p[j])

c2[r]++;

else

break;

}

}

for(r=0;r<f;r++)

 b[r]=c2[r];

for(r=0;r<f;r++)

{

for(j=r;j<f;j++)

{

if(b[r]<b[j])

{

t=b[r];

b[r]=b[j];

b[j]=t;

}

}

}

for(r=0;r<f;r++)

{

if(c2[r]==b[0])

q[r]=p[i];

cout<<" "<<q[r];

}

cout<<"\n";

}

}

}

cout<<"\nThe no of page faults is "<<c;

getch();
}