problem_300.py

from heapq import heappush, heapify


class VoterFraudException(Exception):
    pass


class Candidate:
    def __init__(self, name: int):
        self.name = name
        self.vote_count = 0

    def __eq__(self, other):
        return self.vote_count == other.vote_count

    def __lt__(self, other):
        return self.vote_count < other.vote_count

    def __gt__(self, other):
        return self.vote_count > other.vote_count

    def __repr__(self):
        return "Candidate: {}, Votes: {}".format(self.name, self.vote_count)


class VotingMachine:
    def __init__(self):
        self.votes = dict()
        self.leaderboard = list()
        self.voters = set()

    def cast_vote(self, candidate: int, voter: int):
        if voter in self.voters:
            raise VoterFraudException(
                "Fraud committed by voter {}".format(voter))
        self.voters.add(voter)

        if not candidate in self.votes:
            cand_obj = Candidate(candidate)
            heappush(self.leaderboard, cand_obj)
            self.votes[candidate] = cand_obj
        cand_obj = self.votes[candidate]
        cand_obj.vote_count += 1

    def get_top_three(self):
        heapify(self.leaderboard)
        return [x.name for x in self.leaderboard[-3:]]


def process_votes(vm, file_contents):
    for (candidate, voter) in file_contents:
        vm.cast_vote(candidate, voter)


# Tests
file_contents = [
    (0, 0),
    (0, 1),
    (1, 2),
    (1, 3),
    (1, 4),
    (1, 5),
    (2, 6)
]
vm = VotingMachine()
process_votes(vm, file_contents)
assert vm.get_top_three() == [2, 0, 1]
process_votes(vm, [(2, 0)])