Arith-Geo

Answer

function ArithGeo(arr) {
  const isArithmic = arr => {
    let diff = arr[1] - arr[0];
    for (let i = 2; i < arr.length; i++) {
      if (arr[i] - arr[i - 1] !== diff) {
        return false;
      }
    }
    return true;
  };

  const isGeo = arr => {
    let diff = arr[1] / arr[0];
    for (let i = 2; i < arr.length; i++) {
      if (arr[i] / arr[i - 1] !== diff) {
        return false;
      }
    }
    return true;
  };

  if (isArithmic(arr)) return 'Arithmetic';
  if (isGeo(arr)) return 'Geometric';

  return -1;
}
copy