출처 : https://taesung1993.tistory.com/46
function solution(number, k) {
const arr = [];
for (let i = 0; i < number.length; i++) {
while ( arr[arr.length - 1] < number[i] && k > 0) {
k--;
arr.pop();
}
arr.push(number[i]);
}
arr.splice(number.length - k, k);
return arr.join("");
}