HighFive.java

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.PriorityQueue;

public class HighFive {
 /**
 Description
 There are two properties in the node student id and scores, to ensure that each student will have at least 5 points, find the average of 5 highest scores for each person.


 Example
 Given results = [[1,91],[1,92],[2,93],[2,99],[2,98],[2,97],[1,60],[1,58],[2,100],[1,61]]

 Return
 */
 class Record {
 public int id, score;
 public Record(int id, int score){
 this.id = id;
 this.score = score;
 }
 }

 public Map<Integer, Double> highFive(Record[] results) {
 if (results == null || results.length == 0) return null;
 Map<Integer, PriorityQueue<Integer>> idToScores = new HashMap<>();
 Map<Integer, Double> res = new HashMap<>();
 for (int i = 0; i < results.length; i++) {
 Record r = results[i];
 if (!idToScores.containsKey(r.id)) {
 idToScores.put(r.id, new PriorityQueue<>(5, new Comparator<Integer>() {
 @Override
 public int compare(Integer o1, Integer o2) {
 return o2 - o1;
 }
 }));
 }
 idToScores.get(r.id).add(r.score);
 }
 for (int key : idToScores.keySet()) {
 PriorityQueue<Integer> pq = idToScores.get(key);
 double sum = 0;
 while (!pq.isEmpty()) {
 sum += pq.poll();
 }
 res.put(key, sum / 5);
 }
 return res;
 }
}