1244. Design A Leaderboard

Design A Leaderboard - LeetCode

Design a Leaderboard class, which has 3 functions:

addScore(playerId, score): Update the leaderboard by adding score to the given player’s score. If there is no player with such id in the leaderboard, add him to the leaderboard with the given score. top(K): Return the score sum of the top K players. reset(playerId): Reset the score of the player with the given id to 0 (in other words erase it from the leaderboard). It is guaranteed that the player was added to the leaderboard before calling this function.Initially, the leaderboard is empty.

Example 1: Input: [“Leaderboard”,“addScore”,“addScore”,“addScore”,“addScore”,“addScore”,“top”,“reset”,“reset”,“addScore”,“top”] [[],[1,73],[2,56],[3,39],[4,51],[5,4],[1],[1],[2],[2,51],[3]] Output: [null,null,null,null,null,null,73,null,null,null,141] Explanation: Leaderboard leaderboard = new Leaderboard (); leaderboard.addScore(1,73); // leaderboard = [[1,73]]; leaderboard.addScore(2,56); // leaderboard = [[1,73],[2,56]]; leaderboard.addScore(3,39); // leaderboard = [[1,73],[2,56],[3,39]]; leaderboard.addScore(4,51); // leaderboard = [[1,73],[2,56],[3,39],[4,51]]; leaderboard.addScore(5,4); // leaderboard = [[1,73],[2,56],[3,39],[4,51],[5,4]]; leaderboard.top(1); // returns 73; leaderboard.reset(1); // leaderboard = [[2,56],[3,39],[4,51],[5,4]]; leaderboard.reset(2); // leaderboard = [[3,39],[4,51],[5,4]]; leaderboard.addScore(2,51); // leaderboard = [[2,51],[3,39],[4,51],[5,4]]; leaderboard.top(3); // returns 141 = 51 + 51 + 39;

Constraints:

1 <= playerId, K <= 10000 It’s guaranteed that K is less than or equal to the current number of players. 1 <= score <= 100 There will be at most 1000 function calls.


  • code top, time complexity O(K) + O(NlogK) = O(NlogK)
class Leaderboard:

    def __init__(self):
        self.dic = defaultdict(int)

    def addScore(self, playerId: int, score: int) -> None:
        self.dic[playerId] += score
        

    def top(self, K: int) -> int:
        hp = []
        for score in self.dic.values():
            heapq.heappush(hp, score)
            if len(hp) > K:
                heapq.heappop(hp)
        res = 0
        while hp:
            res += heapq.heappop(hp)
            
# method2:heapify the whole list
#         hp = list(self.dic.values())
#         heapq.heapify(hp)
#         res = sum(heapq.nlargest(K, hp))

        return res
            

    def reset(self, playerId: int) -> None:
        self.dic[playerId] = 0


# Your Leaderboard object will be instantiated and called as such:
# obj = Leaderboard()
# obj.addScore(playerId,score)
# param_2 = obj.top(K)
# obj.reset(playerId)
  • code #treeSet O(K) for top, O(logN) for add and reset
class Leaderboard {
    
    private TreeMap<Integer, Integer> scores; // score, num of players who has this score
    private Map<Integer, Integer> idScore;

    public Leaderboard() {
        // scores = new TreeMap<>(Collections.reverseOrder());
        scores = new TreeMap<>((a, b) -> b - a);
        idScore = new HashMap<>();
    }
    
    public void addScore(int playerId, int score) {
        int oldScore = idScore.getOrDefault(playerId, 0);
        int newScore = oldScore + score;
        idScore.put(playerId, newScore);
        
        if (oldScore != 0){
            //  oldScore count --, if then 0, remove
            int oldCount = scores.get(oldScore);
            if (oldCount == 1){
                scores.remove(oldScore);
            }else{
                scores.put(oldScore, --oldCount);
            }
        }
        
        // add 1 count to newScore
        int oldPlayerNum = scores.getOrDefault(newScore, 0);
        scores.put(newScore, oldPlayerNum + 1);
    }
    
    public int top(int K) {
        int res = 0;
        for (Map.Entry<Integer,Integer> e: scores.entrySet()){
            int score = e.getKey(), count = e.getValue();
            while (count-- > 0){
                K --;
                res += score;
                if (K == 0) break;
            }
            if (K == 0) break;
        }
        return res;
        
    }
    
    public void reset(int playerId) {
        int score = idScore.get(playerId);
        int count = scores.get(score);
        if (count == 1){
            scores.remove(score);
        }else{
            scores.put(score, --count);
        }
        
        idScore.remove(playerId);
    }
}

/**
 * Your Leaderboard object will be instantiated and called as such:
 * Leaderboard obj = new Leaderboard();
 * obj.addScore(playerId,score);
 * int param_2 = obj.top(K);
 * obj.reset(playerId);
 */