An exercise on polyglossy: the same problem solved on multiple languages
Improved all implementations in functional programming languages by make the calculation of the sum of the digits of the test values tail recursive.
2 files changed, 11 insertions, 10 deletions
| Status | File Name | N° Changes | Insertions | Deletions |
| Modified | Elixir/main.ex | 15 | 8 | 7 |
| Modified | script.pl | 6 | 3 | 3 |
diff --git a/Elixir/main.ex b/Elixir/main.ex @@ -59,18 +59,19 @@ defmodule Conjecture do case :ets.lookup(:sums_cache, n) do [{_, sum_n}] -> sum_n [] -> - sum_n = sum n + sum_n = sum_digits n :ets.insert(:sums_cache, {n, sum_n}) sum_n end end - def sum 0 do 0 end + def sum_digits n do sum_digits_tail n, 0 end - def sum n do - d = rem n, 10 - r = div n, 10 + def sum_digits_tail 0, acc do acc end - d + sum r - end + def sum_digits_tail n, acc do + r = rem n, 10 + d = div n, 10 + sum_digits_tail d, (acc + r) + end end
diff --git a/script.pl b/script.pl @@ -3,10 +3,10 @@ % Let S: N -> N be the sum of the digits of a positive integer. % For all A and B in N, S(A + B) = S(A) + S(B) - 9k, where k is an integer. -sum_digits(X, Y) :- sum_digits(X, 0, Y). +sum_digits(X, Y) :- sum_digits_tail(X, 0, Y). -sum_digits(X, Acc, Y) :- X < 10, !, Y is Acc + X. -sum_digits(X, Acc, Y) :- +sum_digits_tail(X, Acc, Y) :- X < 10, !, Y is Acc + X. +sum_digits_tail(X, Acc, Y) :- Q = X div 10, R = X mod 10, Acc1 = Acc + R,