https://www.acmicpc.net/problem/10871
const fs = require('fs');
const input = fs.readFileSync('/dev/stdin').toString().split('\n');
const number = input[0].split(" ");
const arr = input[1].split(" ");
let result = new Array();
for(i=0;i<parseInt(number[0]);i++){
if(parseInt(arr[i])<parseInt(number[1]))result.push(arr[i].toString())
}
let str=result.toString().replace(/\,/g," ");
console.log(str);
정규식이 생각나지 않아서 좀 아쉬웠다.
let str=result.toString().replace(/\,/g," ");