Highly Divisible Triangular Number

1 files changed, 18 insertions, 0 deletions

diff --git a/0012/main.hs b/0012/main.hs
new file mode 100644
index 0000000..d40b1a5
--- /dev/null
+++ b/0012/main.hs
@@ -0,0 +1,18 @@
+divisors num = length $ filter divisable [1..num]
+    where divisable x = num `mod` x == 0
+
+pairDivisors (x,y) = (divisors x) * (divisors y)
+
+triangleNums :: [(Integer,Integer)]
+triangleNums = map toPair [1..]
+    where
+        toPair n = if n `mod` 2 == 0 then
+                      (n `div` 2,n+1)
+                   else
+                      ((n+1) `div` 2, n)
+
+firstWithDivisorNum n = impl triangleNums
+    where impl ((a,b):xs) = if pairDivisors (a,b) >= n then (a * b) else impl xs
+
+main = do
+    putStrLn $ show $ firstWithDivisorNum 500