In this HackerRank java comparator problem in the java programming language you have Given an array of n Player objects, write a comparator that sorts them in order of decreasing score; if 2 or more players have the same score, sort those players alphabetically by name. To do this, you must create a Checker class that implements the Comparator interface, then write an int compare(Player a, Player b) method implementing the Comparator.compare(T o1, T o2) method.

HackerRank Java Comparator problem solution


HackerRank Java Comparator problem solution.

import java.util.*;

class Checker implements Comparator<Player>{
    @Override
    public int compare(Player a, Player b){
        if (a.score == b.score){
            return a.name.compareTo(b.name);//alphabetically
        } else {
            return b.score - a.score;//decreasing 
        }
    }
}
class Player{
    String name;
    int score;
    
    Player(String name, int score){
        this.name = name;
        this.score = score;
    }
}

class Solution {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();

        Player[] player = new Player[n];
        Checker checker = new Checker();
        
        for(int i = 0; i < n; i++){
            player[i] = new Player(scan.next(), scan.nextInt());
        }
        scan.close();
     
        Arrays.sort(player, checker);
        for(int i = 0; i < player.length; i++){
            System.out.printf("%s %s\n", player[i].name, player[i].score);
        }
    }
}


Second solution in java8 programming.

import java.util.*;

// Write your Checker class here
class Checker implements Comparator<Player>{

        public int compare(Player a, Player b) {
            // If 2 Players have the same score
            if(a.score == b.score){
                // Order alphabetically by name
                return a.name.compareTo(b.name);
            }    

            // Otherwise, order higher score first  
            return ((Integer) b.score).compareTo(a.score);
        }
    }
class Player{
    String name;
    int score;
    
    Player(String name, int score){
        this.name = name;
        this.score = score;
    }
}

class Solution {

    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();

        Player[] player = new Player[n];
        Checker checker = new Checker();
        
        for(int i = 0; i < n; i++){
            player[i] = new Player(scan.next(), scan.nextInt());
        }
        scan.close();

        Arrays.sort(player, checker);
        for(int i = 0; i < player.length; i++){
            System.out.printf("%s %s\n", player[i].name, player[i].score);
        }
    }
}