Node.js) 백준 15650번 : N과 M (2)

https://www.acmicpc.net/problem/15650

const fs = require('fs');
const input = fs.readFileSync("/dev/stdin").toString().trim().split(" ").map(v=>+v);

const N = input[0];
const M = input[1];
const arr = [];


for(let i = 1; i<=N; i++){
  arr.push(String(i));
}


function countBits(value){ 
  let count  = 0; 
  while(value>0){ 
    if((value&1)==1) count++; 
    value = value>>1; 
  }
  return count; 
}

function solve(){ 
  let answer = [];
  for( let i  = 0; i<(1<<N); i++){ 
    if(countBits(i)==M){ 
      let str =''; 
      for( let j=0; j<N; j++){ 
        if(i&(1<<j)) str+=arr[j]+' '; 
      }
      answer.push(str);
    }
  }

  answer.sort();
  for(let n = 0; n<answer.length; n++){
    console.log(answer[n]); 
  }
}

solve();