MaroShim

# 3digit * 3digit, which is palindrome

defmodule Problem4 do

  def palindrome?(n) do
    s = to_string(n)
    String.reverse(s) == s
  end
  
  def solve do

MaroShim

# largest factor of 600851475143

defmodule Problem3 do

# http://wende.github.io/2015/09/07/Elixir-n-prime-numbers.html

  def prime?(x), do: (2..round(:math.sqrt(x)) |> Enum.filter(fn a -> rem(x, a) == 0 end) |> length()) == 0

  def solve(num) do
    (2 .. round(:math.sqrt(num)))

MaroShim

# sum of fibonacci numbers which is even and less than 4000000 

# https://elixirforum.com/t/project-euler-problem-2/500/2

defmodule Problem2 do

  def fib_seq do
    Stream.unfold({1,1}, fn {a,b} -> {a, {b, a + b}} end)
  end
  

MaroShim

# less than 1000, multiple of 3 or 5

defmodule Problem1 do

  def solve(limit) do
      1..(limit-1) 
      |> Enum.filter(fn x -> ((rem(x, 3) == 0) || (rem(x, 5) == 0)) end)
      |> Enum.reduce(0, &(&1 + &2))
  end