function findDuplicates(numbers: number[]): number[] {
  const searchDuplicates = [];
  const duplicates = [];

  numbers.forEach( (num) => {
    const isDuplicate = searchDuplicates.filter( ( number ) => number === num );
    if ( isDuplicate.length === 0 ){
      searchDuplicates.push(num);
    } else if (isDuplicate.length > 0) {
      if ( !duplicates.some( (isDuplicate) => isDuplicate == num) )   duplicates.push(num); 
    }
    
  })

  if (duplicates.length <= 0 ) return [];
  return duplicates.sort( (a, b) => a - b );
}

// No modificar: necesario para evaluar el resultado.
export { findDuplicates };