Program to implement Optimal Page replacement algorithm

    
/*Objective implement Optimal Page replacement algorithm
   Author:Rahul kumar */
#include <stdio.h>
#define m 100 
int main()
{
    int no_of_frames,no_of_pages,frames[m],pages[m],temp[m],flag1,flag2,flag3,i,j,k,pos,max,faults=0;
    printf("Enter number of frames: ");
    scanf("%d", &no_of_frames);
    
    printf("Enter number of pages: ");
    scanf("%d", &no_of_pages);
    
    printf("Enter page reference string: ");
    
    for(i = 0; i < no_of_pages; ++i)
  {
        scanf("%d", &pages[i]);
    }
    
    for(i = 0; i < no_of_frames; ++i)
  {
        frames[i] = -1;
    }
    
    for(i = 0; i < no_of_pages; ++i)
  {
        flag1 = flag2 = 0;
        
        for(j = 0; j < no_of_frames; ++j)              //for non empty frame or no fault
    {
            if(frames[j] == pages[i])
         {
                   flag1 = flag2 = 1;
                   break;
               }
        }
        
        if(flag1 == 0)                              //for empty frame 
    {
            for(j = 0; j < no_of_frames; ++j)
      {
                if(frames[j] == -1)
        {
                    faults++;
                    frames[j] = pages[i];
                    flag2 = 1;
                    break;
                }
            }    
        }
        
        if(flag2 == 0)
    {
          flag3=0;
          
            for(j =0; j < no_of_frames; ++j)
      {
              temp[j]=-1;
              
              for(k=i+1;k< no_of_pages;++k)
        {
                if(frames[j]==pages[k])
          {
                  temp[j]=k;
                  break;
                }
              }
            }
            
            for(j = 0; j < no_of_frames; ++j)
      {
              if(temp[j] == -1)
        {
                pos = j;
                flag3 = 1;
                break;
              }
            }
            
            if(flag3==0)
      {
              max=temp[0];
              pos=0;
              
              for(j=1;j < no_of_frames; ++j)
        {
                if(temp[j] > max)
          {
                  max=temp[j];
                  pos=j;
                }
              }             
            }
      
      frames[pos]=pages[i];
      faults++;
        }
        
        printf("\n");
        
        for(j = 0; j < no_of_frames; ++j)
    {
            printf("%d\t", frames[j]);
        }
    }
    
    printf("\n\nTotal Page Faults = %d", faults);
    
    return 0;
}   

Output:

Enter number of frames: 4
Enter number of pages: 10
Enter page reference string: 2
3
4
2
1
3
7
5
4
3

2       -1      -1      -1
2       3       -1      -1
2       3       4       -1
2       3       4       -1
2       3       4       1
2       3       4       1
7       3       4       1
5       3       4       1
5       3       4       1
5       3       4       1

Total Page Faults = 6