【leetcode】1244. Design A Leaderboard

题目如下：

Design a Leaderboard class, which has 3 functions:

1. 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.
2. top(K): Return the score sum of the top K players.
3. reset(playerId): Reset the score of the player with the given id to 0. 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.

解题思路：根据本题对性能要求不是很高，我的方法是记录每个分数出现的次数，top()的时候把分数排序，再加上每个分数的次数，即可求出排名。

代码如下：

class Leaderboard(object):
    def __init__(self):
        self.dic = {}
        self.dic_player = {}
    def addScore(self, playerId, score):
        """
        :type playerId: int
        :type score: int
        :rtype: None
        """
        if playerId not in self.dic_player:
            self.dic_player[playerId] = score
            self.dic[score] = self.dic.setdefault(score,0) + 1
        else:
            ori_score = self.dic_player[playerId]
            self.dic[ori_score] -= 1
            self.dic_player[playerId] += score
            score = self.dic_player[playerId]
            self.dic[score] = self.dic.setdefault(score, 0) + 1

    def top(self, K):
        """
        :type K: int
        :rtype: int
        """
        score_list = sorted(self.dic.iterkeys())[::-1]
        res = 0
        for i in range(len(score_list)):
            if K == 0:break
            elif K >= self.dic[score_list[i]]:
                res += self.dic[score_list[i]] * score_list[i]
                K -= self.dic[score_list[i]]
            elif K < self.dic[score_list[i]]:
                res += K * score_list[i]
                K = 0
        return res

    def reset(self, playerId):
        """
        :type playerId: int
        :rtype: None
        """
        score = self.dic_player[playerId]
        self.dic[score] -= 1
        if self.dic[score] == 0:
            del self.dic[score]
        del self.dic_player[playerId]