数组元素全倒排列并去重

Answer 1

main([1631,1635,3161])

function main(input) {
  var results = [];
  input.forEach(num => {
     const numArray = `${num}`.split('');
     dfs('', numArray);
  })
  return Array.from(new Set(results))
              .map(numString => parseInt(numString, 10))
              .sort();

  function dfs(num, numArray) {
    let length = numArray.length;
    if (length == 0) {
      results.push(num);
      return;
    }

    let i = 0;
    while(i < length) {
      let copy = numArray.slice();
      copy.splice(i, 1);
      dfs(num + numArray[i], copy);
      i++;
    }
  }
}