Python - 예전에 푼 걸 다시 풀어보았다. def solution(participant, completion): name_dict = dict() for name in participant: if name_dict.get(name): name_dict[name] += 1 else: name_dict[name] = 1 for name in completion: count = name_dict[name] if count == 1: del name_dict[name] else: name_dict[name] -= 1 return list(name_dict.keys())[0] # 효율성 X # for name in completion: # participant.remove(name) # return part..