オープンチャットルーム

Solution

import collections
def solution(record):
    output = []
    result = []
    ids = collections.defaultdict(str)
    for r in record:
        command = r.split()
        if command[0] == "Enter":
            ids[command[1]] = command[2]
            output.append((command[1],"Enter"))
        elif command[0] == "Leave":
            output.append((command[1],"Leave"))
        elif command[0] == "Change":
            ids[command[1]] = command[2]

    for id,action in output:
        if action == "Enter":
            result.append(f"{ids[id]}님이 들어왔습니다.")
        elif action == "Leave":
            result.append(f"{ids[id]}님이 나갔습니다.")
    return result