From 9296a4bd149d3161fd06a28f00a18020b4bd1dc4 Mon Sep 17 00:00:00 2001
From: Kshitij <kshitijk@tuta.io>
Date: Tue, 5 Nov 2024 16:42:49 +0530
Subject: [PATCH] Made some minor changes to B7 (page replacement in C++) code.
 - Changed variable names - Indentation and stuff - Added description

---
 Codes/Group B/Code-B7.cpp | 223 +++++++++++++++++++-------------------
 1 file changed, 111 insertions(+), 112 deletions(-)

diff --git a/Codes/Group B/Code-B7.cpp b/Codes/Group B/Code-B7.cpp
index 8908ca2..6d72247 100644
--- a/Codes/Group B/Code-B7.cpp	
+++ b/Codes/Group B/Code-B7.cpp	
@@ -1,136 +1,135 @@
-#include<iostream>
+// Assignment-B7 - Page Replacement in C++ (LRU + Optimal)
+// BEGINNING OF CODE
+#include <cmath>
+#include <complex>
+#include <iostream>
 using namespace std;
 
-int refstring[] = {0, 2, 1, 6, 4, 0, 1, 0, 3, 1, 2, 1};
-int win, hit = 0, miss = 0, res[4], lastUsed[40];
+int refString[] = {0, 2, 1, 6, 4, 0, 1, 0, 3, 1, 2, 1};
+int window = 0, hit = 0, miss = 0, currentPages[4], lastUsed[40];
+int len = sizeof(refString) / sizeof(refString[0]);
 
 int findLRU() {
-    int minIndex = 0;
-    for(int i = 1; i < win; i++){
-        if(lastUsed[i] < lastUsed[minIndex]){
-            minIndex = i;
-        }
+  int min_index = 0;
+  for (int i=1; i<window; i++) {
+    if (lastUsed[i] < lastUsed[min_index]) {
+      min_index = i;
     }
-    return minIndex;
+  }
+  return min_index;
 }
 
-void lru(int rf[], int len)
-{
-    for(int i = 0; i < win; i++) {
-        res[i] = -1;
-        lastUsed[i] = -1;
-    }
+void LRU() {
+  for (int i=0; i<window; i++) {
+    currentPages[i] = -1;
+    lastUsed[i] = -1;
+  }
 
-    for(int j = 0; j < len; j++) {
-        bool hitFlag = false;
-        for(int k = 0; k < win; k++){
-            if (res[k] == rf[j]){
-                hit++;
-                lastUsed[k] = j;
-                hitFlag = true;
-                break;
-            }
-        }
-        if (!hitFlag) {
-            miss++;
-            bool emptyFound = false;
-            for(int k = 0; k < win; k++){
-                if (res[k] == -1){
-                    res[k] = rf[j];
-                    lastUsed[k] = j;
-                    emptyFound = true;
-                    break;
-                }
-            }
-            if(!emptyFound){
-                int lruIndex = findLRU();
-                res[lruIndex] = rf[j];
-                lastUsed[lruIndex] = j;
-            }
-        }
+  for (int i=0; i<len; i++) {
+    bool hitFlag = false;
+    for (int j=0; j<window; j++) {
+      if (currentPages[j] == refString[i]) {
+        hit++;
+        hitFlag = true;
+        lastUsed[j] = i;
+        break;
+      }
     }
-
-    cout<<"\nNo of hits (LRU): "<<hit;
-    cout<<"\nNo of misses (LRU): "<<miss;
+    if (hitFlag == false) {
+      miss++;
+      bool emptyFound = false;
+      for (int j=0; j<window; j++) {
+        if (currentPages[j] == -1) {
+          emptyFound = true;
+          currentPages[j] = refString[i];
+          lastUsed[j] = i;
+          break;
+        }
+      }
+        if (emptyFound == false) {
+          int lru_index = findLRU();
+          currentPages[lru_index] = refString[i];
+          lastUsed[lru_index] = i;
+        }
+      }
+  }
+  cout<<endl<<"----- LRU ------";
+  cout<<endl<<"Number of hits: "<<hit;
+  cout<<endl<<"Number of misses: "<<miss;
 }
 
-int findOptimal(int rf[], int len, int currentIndex)
-{
-    int maxIndex = -1, farthest = currentIndex;
-    for(int i = 0; i < win; i++){
-        int j;
-        for(j = currentIndex + 1; j < len; j++){
-            if(res[i] == rf[j]){
-                if(j > farthest){
-                    farthest = j;
-                    maxIndex = i;
-                }
-                break;
-            }
+int findOptimal(int current_index) {
+  int max_index = -1, farthest = current_index;
+  for (int i=0; i<window; i++) {
+    int j;
+    for (j=current_index+1; j<len; j++) {
+      if (currentPages[i] == refString[j]) {
+        if (j > farthest) {
+          farthest = j;
+          max_index = i;
         }
-        if(j == len)
-            return i;
+        break;
+      }
     }
-    return maxIndex;
+    if (j == len) {
+      return i;
+    }
+  }
+  return max_index;
 }
 
-void optimal(int rf[], int len){
-    hit = 0;
-    miss = 0;
+void Optimal() {
+  hit = 0;
+  miss = 0;
 
-    for(int i = 0; i < win; i++){
-        res[i] = -1;
+  for (int i=0; i<window; i++) {
+    currentPages[i] = -1;
+  }
+
+  for (int i=0; i<len; i++) {
+    bool hitFlag = false;
+    for (int j=0; j<window; j++) {
+      if (currentPages[j] == refString[i]) {
+        hit++;
+        hitFlag = true;
+        break;
+      }
     }
-
-    for(int j = 0; j < len; j++){
-        bool hitFlag = false;
-        for(int k = 0; k < win; k++){
-            if (res[k] == rf[j]){
-                hit++;
-                hitFlag = true;
-                break;
-            }
-        }
-        if (!hitFlag){
-            miss++;
-            bool emptyFound = false;
-            for(int k = 0; k < win; k++){
-                if (res[k] == -1){
-                    res[k] = rf[j];
-                    emptyFound = true;
-                    break;
-                }
-            }
-            if(!emptyFound){
-                int optimalIndex = findOptimal(rf, len, j);
-                res[optimalIndex] = rf[j];
-            }
+    if (hitFlag == false) {
+      miss++;
+      bool emptyFound = false;
+      for (int j=0; j<window; j++) {
+        if (currentPages[j] == -1) {
+          emptyFound = true;
+          currentPages[j] = refString[i];
+          break;
         }
+      }
+      if (emptyFound == false) {
+        int optimal_index = findOptimal(i);
+        currentPages[optimal_index] = refString[i];
+      }
     }
-
-    cout<<"\nNo of hits (Optimal): "<<hit;
-    cout<<"\nNo of misses (Optimal): "<<miss;
+  }
+  cout<<endl<<"----- OPTIMAL -----";
+  cout<<endl<<"Number of hits: "<<hit;
+  cout<<endl<<"Number of misses: "<<miss;
 }
 
-void display()
-{
-    cout<<"\nPages in window are: \n";
-    for(int i = 0; i < win; i++){
-        cout<<res[i]<<"\n";
-    }
+void display() {
+  cout<<endl<<"Current pages are:\t";
+  for (int i=0; i<window; i++) {
+    cout<<currentPages[i]<<" ";
+  }
+  cout<<endl;
 }
 
-int main()
-{
-    cout<<"\nEnter window size: ";
-    cin>>win;
-    int len = sizeof(refstring)/sizeof(refstring[0]);
-
-    cout<<"\nBy LRU algorithm: ";
-    lru(refstring, len);
-    display();
-
-    cout<<"\n\nBy Optimal Algorithm: ";
-    optimal(refstring, len);
-    display();
+int main() {
+  cout<<endl<<"Enter window size:\t";
+  cin>>window;
+  LRU();
+  display();
+  Optimal();
+  display();
 }
+// END OF CODE