https://programmers.co.kr/learn/courses/30/lessons/42888?language=javascript
function solution(record) {
const userInfo = {}
const action = []
const stateMapping = {
'Enter': '님이 들어왔습니다.',
'Leave': '님이 나갔습니다.'
}
record.forEach((v) => {
const [state, id, nick] = v.split(' ')
if(state !== "Change") {
action.push([state, id]);
}
if(nick) {
userInfo[id] = nick
}
})
return action.map(([state, uid]) => {
return `${userInfo[uid]}${stateMapping[state]}`
})
}