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FIFO, LRU and Optimal.java
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FIFO, LRU and Optimal.java
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// Program to simulate Page replacement algorithm: FIFO LRU and Optimal:-
// 1.FIFO And LRU:-
import java.util.*;
public class Main {
public static void main(String[] args) {
pr();
}
static void pr(){
Scanner sc = new Scanner(System.in);
System.out.println("Page Replacement : ");
System.out.println("Enter 1 for FIFO ");
System.out.println("Enter 2 for LRU ");
System.out.printf("Enter Choice : ");
int x = sc.nextInt();
System.out.printf("Length of String : " );
int n = sc.nextInt();
int fr = 3;
int ref[] = new int[n];
for (int i = 0; i < n; i++){
ref[i] = sc.nextInt();
}
// FIFO
HashMap<Integer,Integer> map = new HashMap<>();
ArrayList<ArrayList<Integer>> arr = new ArrayList<>();
for(int i = 0 ; i <= n ; i++){
arr.add(new ArrayList<>());
}
for(int i = 0 ; i < fr ; i++){
arr.get(0).add(-1);
}
int ct = 1;
int hit = 0;
if(x == 1 && n > 0){
int indx= 0;
for(int i = 1 ; i <= n ; i++){
int curr = ref[i-1];
arr.get(i).addAll(arr.get(i-1));
if(!map.containsKey(curr)){
if(indx < fr) arr.get(i).set((indx),ref[i-1]);
else{
int min = Integer.MAX_VALUE;
int temp = 0;
for(int j : map.keySet()){
if(map.get(j) < min){
min = map.get(j);
temp = j;
}
}
for(int j = 0 ; j < fr ; j++){
if(arr.get(i).get(j) == temp){
arr.get(i).set(j,curr);
break;
}
}
map.remove(temp);
}
map.put(ref[i-1],ct++);
indx++;
}else{
hit++;
}
}
}else if(x == 2 && n > 0 ){
//LRU
int indx= 0;
for(int i = 1 ; i <= n ; i++){
int curr = ref[i-1];
arr.get(i).addAll(arr.get(i-1));
if(!map.containsKey(curr)){
if(indx < fr) arr.get(i).set(indx,ref[i-1]);
else{
int min = Integer.MAX_VALUE;
int temp = 0;
for(int j : map.keySet()){
if(map.get(j) < min){
min = map.get(j);
temp = j;
}
}
for(int j = 0 ; j < fr ; j++){
if(arr.get(i).get(j) == temp){
arr.get(i).set(j,curr);
break;
}
}
map.remove(temp);
}
indx++;
}else{
hit++;
}
map.put(ref[i-1],ct++);
}
}
// Output
System.out.println();
for(int i = 0 ; i <= n ; i++){
for(int j = 0 ; j < fr ; j++){
System.out.printf(arr.get(i).get(j) + " ");
}
System.out.println();
}
System.out.println("Total Page Fault : " + (n - hit));
System.out.println("Total Page Hit : " + hit);
sc.close();
}
}
// 2. Optimal Page Replacement Algorithm:-
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Main {
public static void main(String[] args) throws IOException
{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int rl, fr, pt = 0, hit = 0, fault = 0;
boolean isFull = false;
int buffer[];
int reference[];
int mem_layout[][];
System.out.println("\nENTER THE NUMBER OF FRAMES: ");
fr = Integer.parseInt(br.readLine());
System.out.println("\nENTER THE LENGTH OF REFERENCE STRING: ");
rl = Integer.parseInt(br.readLine());
reference = new int[rl];
mem_layout = new int[rl][fr];
buffer = new int[fr];
for(int j = 0; j < fr; j++)
buffer[j] = -1;
System.out.println("\nENTER THE REFERENCE STRING: ");
for(int i = 0; i < rl; i++)
{
reference[i] = Integer.parseInt(br.readLine());
}
System.out.println();
for(int i = 0; i < rl; i++)
{
int search = -1;
for(int j = 0; j < fr; j++)
{
if(buffer[j] == reference[i])
{
search = j;
hit++;
break;
}
}
if(search == -1)
{
if(isFull)
{
int index[] = new int[fr];
boolean index_flag[] = new boolean[fr];
for(int j = i + 1; j < rl; j++)
{
for(int k = 0; k < fr; k++)
{
if((reference[j] == buffer[k]) && (index_flag[k] == false))
{
index[k] = j;
index_flag[k] = true;
break;
}
}
}
int max = index[0];
pt = 0;
if(max == 0)
max = 200;
for(int j = 0; j < fr; j++)
{
if(index[j] == 0)
index[j] = 200;
if(index[j] > max)
{
max = index[j];
pt = j;
}
}
}
buffer[pt] = reference[i];
fault++;
if(!isFull)
{
pt++;
if(pt == fr)
{
pt = 0;
isFull = true;
}
}
}
for(int j = 0; j < fr; j++)
mem_layout[i][j] = buffer[j];
}
for(int i = 0; i < fr; i++)
{
for(int j = 0; j < rl; j++)
System.out.printf("%3d ",mem_layout[j][i]);
System.out.println();
}
System.out.println("\nTOTAL NUMBER OF HIT: " + hit);
System.out.println("\nHIT RATIO: " + (float)((float)hit/rl));
System.out.println("\nTOTAL NUMBER OF PAGE FAULT: " + fault);
}
}