Sorting: Comparator


Problem Statement :


Comparators are used to compare two objects. In this challenge, you'll create a comparator and use it to sort an array. The Player class is provided in the editor below. It has two fields:

1. name : a string.
2. score : an integer.
Given an array of  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 ascending 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. In short, when sorting in ascending order, a comparator function returns -1 if a < b, 0 if , a = b and 1 if a > b.

Declare a Checker class that implements the comparator method as described. It should sort first descending by score, then ascending by name. The code stub reads the input, creates a list of Player objects, uses your method to sort the data, and prints it out properly.


Input Format

The first line contains an integer, n , the number of players.
Each of the next n lines contains a player's  name and score, a string and an integer.

Constraints

0  <=   score  <=  1000
Two or more players can have the same name.
Player names consist of lowercase English alphabetic letters.
Output Format

You are not responsible for printing any output to stdout. Locked stub code in Solution will instantiate a Checker object, use it to sort the Player array, and print each sorted element.



Solution :



                        In  C ++ :





#include <bits/stdc++.h>
using namespace std;

struct Player {
    string name;
    int score;
};

bool compare(Player a, Player b) {   
    if(a.score == b.score)
        return a.name < b.name;
    return a.score > b.score;
}   


vector<Player> comparator(vector<Player> players) {
    sort(players.begin(), players.end(), compare);
    return players;
}

int main() {
    
    int n;
    cin >> n;
    vector< Player > players;
    string name;
    int score;
    for(int i = 0; i < n; i++){
        cin >> name >> score;
        Player p1;
        p1.name = name, p1.score = score;
        players.push_back(p1);
    }
    
    vector<Player > answer = comparator(players);
    for(int i = 0; i < answer.size(); i++) {
        cout << answer[i].name << " " << answer[i].score << endl;
    }
    return 0;
}
                    

                        In Java :




import java.util.*;

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);
    }
}
                    

                        In Python3 :





from functools import cmp_to_key
class Player:
    def __init__(self, name, score):
        self.name = name
        self.score = score
    def __repr__(self):
        self.name = ""
        self.score = 0
    def comparator(a, b):
        if a.score == b.score:
            if a.name > b.name:
                return 1
            else:
                return -1
        if a.score > b.score:
            return -1
        else:
            return 1
                    



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