Ranking (with. Java)

This is an article that looks into the “ranking (with. Java)” problem.

As I solve coding test problems, I look back on the problems I solved and look into different solution methods to get to know myself.

Let’s look at the problem first.

problem

We want to rank students based on the average of their English and math scores.

Given a two-dimensional integer array score containing English and math scores, complete the solution function to return an array containing ranks based on the average of the English and math scores.

Restrictions

• 0 ≤ score[0], score[1] ≤ 100
• 1 ≤ score length ≤ 10
• The element length of score is 2.
• score does not have duplicate elements.

Input/Output Example

My solution to the problem

import java.util.*;
class Solution {
 public int[] solution(int[][] score) {
 int[] answer = new int[score.length];
 List<Integer> list = new ArrayList<>();

 for(int[] tempArray : score){
 list.add(tempArray[0] + tempArray[1]);
 }

 list.sort(Comparator.reverseOrder());

 for(int i = 0; i < score.length; i++){
 answer[i] = list.indexOf(score[i][0] + score[i][1]) + 1;
 }
 return answer;
 }
}

Solution explanation

The solution method takes a two-dimensional integer array score as input.

This array represents each student’s English and math scores.

First, create a list that will contain the sum of each student’s English and math scores.

By iterating through the array score, each student’s English score and math score are added together and added to the list.

Sort in descending order based on the combined score.

Once again, iterate over the array score and determine the rank by checking which student’s combined score is the largest.

After determining the rank, store that rank in the answer array.

Finally, it returns an answer array.

The reason for ranking students this way is based on the sum of their scores, because using averages can cause decimal problems.