function subsetSum(a, n) {
  if (a.length === 0) return false

  const el = a[0]
  if (el === n) return [ el ]

  const rest = a.slice(1)

  const resultWithEl = subsetSum(rest, n - el)
  if (resultWithEl) return resultWithEl.concat([ el ])

  const resultWithoutEl = subsetSum(rest, n)
  if (resultWithoutEl) return resultWithoutEl

  return false
}