一、将数字拆开转为数组

/**
@param{number} num 
@returns {array}
*/
function setNumList(num) {
  let nums = [];
  for (item of num.toString().split("")) {
    nums.push(parseInt(item))
  }
  return nums;
}
console.log(setNumList(35231));    // [3,5,2,3,1]