head.md

ekvation 1:

15h + k + 0,25m = 100 (1)

multiplicerad med 4 för att få heltal:

60h + 4k + m = 400 (1)

ekvation 2:

h + k + m = 100 (2)

sätt in (2) i (1) ger:

60(100 - k - m) + 4k + m = 400

5600 = 56k + 59m

k = (5600 - 59m)/56 = 100 - 59m/56

enda heltalslösningen är för m = 56 vilket ger k = 41

h = 100 - k - m = 3

alltså:

3 hundar: 3 x 15 = 45 kr

41 katter: 41 kr

56 möss: 56 x 0,25 = 14 kr

katze.clj

(def combinations
  (for [dog (range 1 98) cat (range 1 98)
        :when (>= 98 (+ dog cat))]
    (let [mouse (- 100 dog cat)]
      {:dog dog :cat cat :mouse mouse})))

(defn winner? [{:keys [dog cat mouse]}]
  (== 100 (+ (* 15 dog) (* 1 cat) (* 0.25 mouse))))

(defn find-winner []
  (filter winner? combinations))

(println (find-winner))

katze.ps1

$range = 1..98
$combinations = $range | % { 
        $dog = $_ 
        $range | % { 
            $cat = $_ 
            return @{"Dog" = $dog; "Cat" = $cat; "Mouse" = 100 - $dog -$cat } 
        } 
    } | ? { $_.Mouse -gt 0 }

function winner?($combination) {
    return $combination.Dog * 15 + $combination.Cat * 1 + $combination.Mouse * 0.25 -eq 100
}

$winner = $combinations | ? { winner? $_ }

katze_oneliner.ps1

1..98 | % { 
    $dog = $_ 
    1..98 | % { 
      $cat = $_ 
      @{
        "Dog" = $dog 
        "Cat" = $cat
        "Mouse" = 100 - $dog -$cat 
      } 
    } 
  } | ? { 
      $_.Mouse -gt 0 
  } | ? { $_.Dog * 15 + $_.Cat * 1 + $_.Mouse * 0.25 -eq 100 }