export function sortByFrequency(nums: number[]): number[] {
  
  const seen = new Map<number, number>()

  nums.forEach(n => seen.set(n, (seen.get(n) || 0) + 1))

  return [...nums].sort((a, b) => 
    (seen.get(b)! - seen.get(a)!) || (a - b)
  );
}