Problem

There are two properties in the node studentidandscores, 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

思路

• 求每个人的top 5, 于是需要一个hash table

    public Map<Integer, Double> highFive(Record[] results) {
        Map<Integer, PriorityQueue<Integer>> map = new HashMap<>();
        Map<Integer, Double> res = new HashMap<>();
        if (results == null || results.length == 0) {
            return res;
        }

        for (Record r: results) {
            if (!map.containsKey(r.id)) {
                map.put(r.id, new PriorityQueue<Integer>());
            } 
            PriorityQueue<Integer> heap = map.get(r.id);
            heap.offer(r.score);
            if (heap.size() > 5) {
                heap.poll();
            }
        }
        for (Integer key: map.keySet()) {
            double sum = 0;
            for (Integer s: map.get(key)) {
                sum += s;
            }
            res.put(key, sum / 5);
        }
        return res;
    }