https://programmers.co.kr/learn/courses/30/lessons/12901
function solution(a, b) { var answer = ''; const week = ['SUN', 'MON', 'TUE', 'WED', 'THU', 'FRI', 'SAT']; let date = new Date(`2016-${a}-${b}`).getDay(); answer = week[date]; return answer; }