SPOS - Least Recently Used [LRU] Program

import java.util.HashMap;

import java.util.HashSet;

import java.util.Iterator;

import java.util.Scanner;

class lru

{

static int pageFaults(int pages[], int n, int frame)

{

HashSet<Integer> s = new HashSet<>(frame);

HashMap<Integer, Integer> indexes = new HashMap<>();

int page_faults = 0;

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

{

if (s.size() < frame)

{

if (!s.contains(pages[i]))

{

s.add(pages[i]);

page_faults++;

}

indexes.put(pages[i], i);

}

else

{

if (!s.contains(pages[i]))

{

int lru = Integer.MAX_VALUE, val=Integer.MIN_VALUE;

Iterator<Integer> itr = s.iterator();

while (itr.hasNext()) {

int temp = itr.next();

if (indexes.get(temp) < lru)

{

lru = indexes.get(temp);

val = temp;

}

}

s.remove(val);

indexes.remove(val);

s.add(pages[i]);

page_faults++;

}

indexes.put(pages[i], i);

}

}

return page_faults;

}

public static void main(String args[])

{

Scanner sc = new Scanner(System.in);

System.out.println("Enter Number Of Reference: ");

int nr = sc.nextInt();

System.out.println("Enter Number Of Frames: ");

int frame = sc.nextInt();

int pages [] = new int[nr];

System.out.println("Enter Reference:");

for(int i=0 ; i<nr ; i++){

pages[i] = sc.nextInt();

}

// 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2

//f= 6 & h=7

System.out.println("Page Fault is : " + pageFaults(pages, pages.length, frame));

System.out.println("Page Hit is: " +(nr - pageFaults(pages, pages.length, frame)));

sc.close();

}

}