Информатика д/з

12_04_17.txt

факториал Ruby

2.3.1 :001 > def factorial n
2.3.1 :002?>     n > 1 ? n * factorial(n - 1) : 1
2.3.1 :003?>   end
2.3.1 :004 > factorial(3)
 => 6
 
Фибоначчи Ruby one line
 2.5.1 :025 > print (1...10).inject( [0, 1] ) { | fib | fib << fib.last(2).inject(:+) }
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55] => nil
2.5.1 :026 >
 
 факториал Elixir
 
iex(1)> defmodule Factorial do
...(1)> def factorial(0), do: 1
...(1)> def factorial(n) when n > 0 do
...(1)> n * factorial(n - 1)
...(1)> end
...(1)> end
iex(2)> Factorial.factorial(4)
24
iex(3)> Factorial.factorial(5)
120

квадратное уравнение Elixir

iex(6)> defmodule SqEv do
...(6)>   def sq_ev(a, b, c) do
...(6)>     solve(descriminant(a, b, c), a, b)
...(6)>   end
...(6)>
...(6)>   defp solve(0, a, b), do: %{x1: -b/2*a, x2: -b/2*a}
...(6)>   defp solve(descr, a, b) when descr > 0 do
...(6)>     %{x1: (-b - :math.sqrt(descr))/2*a, x2: (-b + :math.sqrt(descr))/2*a}
...(6)>   end
...(6)>   defp solve(_descr, _a, _b), do: %{x1: nil, x2: nil}
...(6)>
...(6)>   defp descriminant(a, b, c) do
...(6)>     b*b - 4*a*c
...(6)>   end
...(6)> end

iex(18)> SqEv.sq_ev(2, -3, 4)
%{x1: nil, x2: nil}
iex(22)> SqEv.sq_ev(9, 6, 1)
%{x1: -27.0, x2: -27.0}

числа Фибоначчи Elixir

iex(29)> defmodule Fib do
...(29)>   def fib(n) when n == 1, do: 1
...(29)>   def fib(n) when n == 2, do: 1
...(29)>   def fib(n) do
...(29)>     fib(n-1) + fib(n-2)
...(29)>   end
...(29)> end

iex(32)> Fib.fib(6)
8
iex(33)> Fib.fib(7)
13