1086. High Five

Given a list of the scores of different students, items, where items[i] = [IDi, scorei] represents one score from a student with IDi, calculate each student's top five average.

Return the answer as an array of pairs result, where result[j] = [IDj, topFiveAveragej] represents the student with IDj and their top five average. Sort result by IDj in increasing order.

A student's top five average is calculated by taking the sum of their top five scores and dividing it by 5 using integer division.

Example 1:

Input: items = [[1,91],[1,92],[2,93],[2,97],[1,60],[2,77],[1,65],[1,87],[1,100],[2,100],[2,76]]
Output: [[1,87],[2,88]]
Explanation: 
The student with ID = 1 got scores 91, 92, 60, 65, 87, and 100. Their top five average is (100 + 92 + 91 + 87 + 65) / 5 = 87.
The student with ID = 2 got scores 93, 97, 77, 100, and 76. Their top five average is (100 + 97 + 93 + 77 + 76) / 5 = 88.6, but with integer division their average converts to 88.

Example 2:

Input: items = [[1,100],[7,100],[1,100],[7,100],[1,100],[7,100],[1,100],[7,100],[1,100],[7,100]]
Output: [[1,100],[7,100]]

Constraints:

• 1 <= items.length <= 1000

• items[i].length == 2

• 1 <= IDi <= 1000

• 0 <= scorei <= 100

• For each IDi, there will be at least five scores.

class Solution {
    public int[][] highFive(int[][] items) {
        TreeMap<Integer,Queue<Integer>> map = new TreeMap<>();
        
        for(int[] item : items){
            int key = item[0];
            int score = item[1];
            if(!map.containsKey(key)){
                map.put(key, new PriorityQueue<>((a,b) -> b-a));
            }
            map.get(key).add(score);
        }
        List<int[]> res = new ArrayList<>();
        for(int key : map.keySet()){
            int sum = 0;
            for(int i=0; i<5; i++){
                sum += map.get(key).poll();
            }
            res.add(new int[]{key,sum/5});
        }
        int[][] ans = new int[res.size()][];
        return res.toArray(ans);
    }
}