[Baekjoon] [1371] 가장 많은 글자

https://www.acmicpc.net/problem/1371

1371번: 가장 많은 글자

const fs = require('fs');
let input = fs.readFileSync('/dev/stdin').toString().split('\n');

const dic = {};

input.forEach(i => {
    let arr = i.split("").filter(d => d !== ' ');
    arr.forEach((a) => {
        if(dic[a] === undefined) {
            dic[a] =1;
        } else {
            dic[a] +=1;
        }
    })
}) ;

const keys = Object.keys(dic);

let answer = [];

keys.forEach(k => {
   answer.push([k, dic[k]]);
});

answer.sort(function(a,b){
    return b[1] - a[1];
})

const max = answer[0][1];
answer = answer.filter(a => a[1] === max);

const print =[];
answer.forEach(a => {
    print.push(a[0]);
});
print.sort();

console.log(print.join(''));