1 files changed, 15 insertions, 0 deletions
diff --git a/H31.hs b/H31.hs
new file mode 100644
index 0000000..9c321ca
--- /dev/null
+++ b/H31.hs
@@ -0,0 +1,15 @@
+import System.Random
+
+isPrime :: Integral a => a -> Bool
+isPrime x = and $ fmap ((/=0).(mod x)) [2..(x-1)]
+
+testn = 10
+
+isPrimeT 2 = True
+isPrimeT x = and $ fmap ((/=0).(fstPow x (x-1))) $ take testn $ randomRs (2,(x-1)) (mkStdGen 100)
+
+fstPow _ 1 x = x
+fstPow m y x 
+    | y `mod` 2 == 1 = (x * (fstPow m (y `div` 2) (sqr x))) `mod` m
+    | otherwise = fstPow m (y `div` 2) (sqr x)
+    where sqr a = (a*a) `mod` m