백준 6603 로또 (백트래킹)

문제

제한사항

입출력 예

풀이

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

const solution = (n, arr) => {
  let answer = [];
  let visited = new Array(n).fill(0);
  let tmp = [];
  const dfs = (index, cnt) => {
    if (cnt === 6) {
      answer.push(tmp.join(" "));
    } else {
      for (let i = index; i < n; i++) {
        if (!visited[i]) {
          visited[i] = 1;
          tmp.push(arr[i]);
          dfs(i, tmp.length);
          tmp.pop();
          visited[i] = 0;
        }
      }
    }
  };
  dfs(0);
  return answer.join("\n");
};

for(let x of input){
    let arr = x.split(" ").map(e => +e);
    let n = arr.shift();
    console.log(solution(n, arr));
    console.log("");
}

• 조합문제이다.
• 입력, 출력을 착각해서 괜한 시간을 잡아먹었다. 잘 읽자!

const combinations = function* (elements, selectNumber) {
  for (let i = 0; i < elements.length; i++) {
    if (selectNumber === 1) {
      yield [elements[i]];
    } else {
      const fixed = elements[i];
      const rest = combinations(elements.slice(i + 1), selectNumber - 1);

      for (const a of rest) {
        yield [fixed, ...a];
      }
    }
  }
};

const input = ["7 1 2 3 4 5 6 7", "8 1 2 3 5 8 13 21 34", "0"];
const sol = (str) => {
  const [n, ...arr] = str.split(" ").map(Number);

  const answer = [];
  for (let number of combinations(arr, 6)) {
    answer.push(number.join(" "));
  }

  return answer.join("\n");
};

for (let x of input) {
  console.log(sol(x));
  console.log("");
}

• 제너레이터를 이용한 방법