Refactor library class and improve code readability

Google_Hash_Code_2020.java

@@ -1,117 +1,105 @@
-//This is my submission for the Google Hash Code 2020 Online Qualification Round. In fetched me a score of 15,435,636
-//and a Global Rank of 5364 out of 10724 teams.
+import java.util.*;
 
-//A few modifiactions can be done to improve the code and score further.
+// Class representing a Library
+class Library {
+    int id;
+    int books;
+    int signup;
+    int booksPerDay;
+    ArrayList<Integer> bookIDs;
 
-import java.util.*;
+    Library(int id, int books, int signup, int booksPerDay, ArrayList<Integer> bookIDs) {
+        this.id = id;
+        this.books = books;
+        this.signup = signup;
+        this.booksPerDay = booksPerDay;
+        this.bookIDs = bookIDs;
+    }
+}
 
-//class to store details of each library
-class library{
-    int id; //unique Library ID
-    int books; //number of books in library
-    int signup; //Sign up time
-    int booksPerDay; //number of books that can be processed per day
-    ArrayList<Integer> bookIDs; //IDs of books in the library
-    library(int i,int b, int s, int bp, ArrayList<Integer> bIDs){
-        id = i;
-        books = b;
-        signup = s;
-        booksPerDay = bp;
-        bookIDs = bIDs;
+// Comparator for sorting libraries by signup time (greedy heuristic)
+class SortBySignup implements Comparator<Library> {
+    public int compare(Library a, Library b) {
+        return a.signup - b.signup;
     }
 }
 
-class SortbySignup implements Comparator<library> 
-{ 
-    // Used for sorting in ascending order of library sign up time
-    public int compare(library a, library b) 
-    { 
-        return a.signup - b.signup; 
-    } 
-} 
+public class hc {
 
+    public static void main(String[] args) {
 
+        Scanner sc = new Scanner(System.in);
 
-public class hc {
+        int totalBooks = sc.nextInt();
+        int numOfLib = sc.nextInt();
+        int totalDays = sc.nextInt();
+
+        int[] bookScore = new int[totalBooks];
+
+        for (int i = 0; i < totalBooks; i++) {
+            bookScore[i] = sc.nextInt();
+        }
+
+        // Store libraries
+        HashMap<Integer, Library> map = new HashMap<>();
+
+        for (int i = 0; i < numOfLib; i++) {
+
+            int books = sc.nextInt();
+            int signup = sc.nextInt();
+            int bpd = sc.nextInt();
+
+            ArrayList<Integer> bid = new ArrayList<>();
+
+            for (int j = 0; j < books; j++) {
+                bid.add(sc.nextInt());
+            }
+
+            map.put(i, new Library(i, books, signup, bpd, bid));
+        }
+
+        // Convert to list for sorting
+        ArrayList<Library> libs = new ArrayList<>(map.values());
+        libs.sort(new SortBySignup());
 
-	public static void main(String[] args) {
-		// TODO Auto-generated method stub
-		Scanner s = new Scanner(System.in);
-        	int totalBooks = s.nextInt();
-        	int numOfLib = s.nextInt();
-        	int totalDays = s.nextInt(); //total number of days where libraries can sign-up and books can be proceesed
-        	int cost[] = new int[totalBooks]; //to store cost of each book
-
-        	for(int i=0;i<totalBooks;i++) cost[i] = s.nextInt();
-
-		//to store Library Info with it's Unique ID
-        	HashMap<Integer,library> map = new HashMap<Integer,library>();
-
-		//storing information of all libraries
-        	for(int i=0;i<numOfLib;i++){
-            		int books = s.nextInt(); //num of books in library
-            		int signup = s.nextInt(); //Sign-up time of library
-            		int bpd = s.nextInt(); //number of books that can be processed per day
-
-			//to store book IDs of books in the library
-            		ArrayList<Integer> bid = new ArrayList<Integer>();
-
-            		for(int j=0;j<books;j++){
-                		bid.add(s.nextInt());
-            		}
-
-            		library lib = new library(i,books, signup, bpd, bid);
-            		map.put(i,lib);
-        	}
-
-		//sorting libraries by sign-up time
-        	ArrayList<library> sortedBySignup = new ArrayList(map.values());
-        	Collections.sort(sortedBySignup, new SortbySignup());
-
-		//Map to store Library ID and the number of days when the books can be shipped
-        	HashMap<Integer,Integer> map2 = new HashMap<Integer,Integer>();
-        	int val = totalDays;
-        	int i = 0;
-
-		//calculating shipment days for each library
-        	while(i<numOfLib && val>0){
-            		library ll = sortedBySignup.get(i);
-            		int remDays = val - ll.signup;
-            		int shipment = remDays*ll.booksPerDay;
-            		map2.put(ll.id,shipment);
-            		val-=ll.signup;
-            		i++;
-        	}
-
-		//store library IDs to be displayed on console
-        	ArrayList<Integer> sol = new ArrayList<Integer>();
-        	int cntLibs = 0;
-
-
-        	for(Map.Entry<Integer,Integer> entry : map2.entrySet()){
-            		int ID = entry.getKey();
-            		int ship = entry.getValue();
-            		if(ship>0){ //to check for a valid value
-                		cntLibs++;
-                		sol.add(ID);
-            		}
-        	}
-
-		//Printing solution
-       	 	System.out.println(cntLibs); //number of libraries
-        	for(int j=0;j<cntLibs;j++){
-            		int ID = sol.get(j);
-            		int shipBooks = map2.get(ID);
-           	 	library llll = map.get(ID);
-            		ArrayList<Integer> bid = llll.bookIDs;
-            		shipBooks = Math.min(bid.size(),shipBooks);
-            		System.out.println(ID+" "+shipBooks);
-
-            		for(int k=0;k<shipBooks;k++){
-                		System.out.print(bid.get(k)+" ");
-            		}
-            		System.out.println();
-        	}
-	}
+        // Result storage
+        ArrayList<Integer> selectedLibs = new ArrayList<>();
 
+        int remainingDays = totalDays;
+
+        for (Library lib : libs) {
+
+            if (remainingDays <= lib.signup) break;
+
+            remainingDays -= lib.signup;
+
+            int shipCapacity = remainingDays * lib.booksPerDay;
+
+            if (shipCapacity > 0) {
+                selectedLibs.add(lib.id);
+            }
+        }
+
+        // Output
+        System.out.println(selectedLibs.size());
+
+        for (int id : selectedLibs) {
+
+            Library lib = map.get(id);
+
+            int remainingDaysAfterSignup = totalDays - lib.signup;
+            int shipCapacity = remainingDaysAfterSignup * lib.booksPerDay;
+
+            shipCapacity = Math.min(shipCapacity, lib.bookIDs.size());
+
+            System.out.println(id + " " + shipCapacity);
+
+            for (int k = 0; k < shipCapacity; k++) {
+                System.out.print(lib.bookIDs.get(k) + " ");
+            }
+            System.out.println();
+        }
+
+        sc.close();
+    }
 }