Kata

Design a Leaderboard class with 3 functions:

• addScore(playerId, score): When given an existing player, it increments their score, otherwise, it adds the player to the leaderboard with the given score.
• top(k): Returns the sum of the scores of the top k players.
• reset(playerId): Resets the score of the player with the given id to 0.

Note that initially, the leaderboard is empty.

Handle invalid cases for each function. E.g. Attempting to reset the score of a player who is not on the leaderboard.