takuma7

import System.IO

main = do
    putStrLn $ biggest "0" [ show (a*b) | a <- [100..999], b <- [100..999], isPalindromicNum (show (a*b))]

isPalindromicNum []     = True
isPalindromicNum (_:[]) = True
isPalindromicNum (x:xs) | x == last xs  = isPalindromicNum (init xs)
                        | otherwise = False

takuma7

import System.IO

main = do
    putStrLn $ show $ last $ filter ((== 0) . (mod 600851475143)) (takeWhile (< (truncate (sqrt 600851475143))) prime)

prime = 2:f [3] [3,5..]
    where f (x:xs) ys   =   let (ps, qs) = span (< x^2) ys
                            in  ps ++ f (xs ++ ps) [z | z <- qs, z `mod` x /= 0]

takuma7

import System.IO

main = do
    putStrLn $ show $ sum $ filter even $ takeWhile ((>) 4000000) fib

fib = 1:2:[ a+b | (a,b) <- zip fib (tail fib)]

takuma7

import System.IO

main = do
    putStrLn $ show $ sum $ filter judge [1..999]
    
judge a | a `mod` 3 == 0 || a `mod` 5 == 0  = True
        | otherwise = False

takuma7

#include <stdio.h>

int main(void){
  printf("Hello World!\n"); //this is a test
}