/*
    Enter, Leave, Change
    + uid1234 Muzi -> Prodo [hash.set("uid1234", "Muzi")]
    + uid4567 Prodo -> Ryan [hash.set("uid4567", "Prodo")]
    - uid1234 Muzi -> Prodo
    + uid1234 Prodo
    c uid4567 Prodo -> Ryan
*/
 
function solution(record) {
    let hash = new Map();
    
    for(const value of record) {
        const actionArr = value.split(" ");
        
        if (actionArr[0] == "Enter" || actionArr[0] == "Change") {
            hash.set(actionArr[1], actionArr[2]);
        }
    }
    
    let result = [];
    
    for(const value of record) {
        const actionArr = value.split(" ");
        
        let message = "";
        
        if (actionArr[0] == "Enter") {
            message = `${hash.get(actionArr[1])}님이 들어왔습니다.`
        } else if (actionArr[0] == "Leave") {
            message = `${hash.get(actionArr[1])}님이 나갔습니다.`
        }
        
        if (message) {
            result.push(message);
        }
    }
    return result;
}