haskell problem 22, 24, 25, 29, 39, 40, 45, 53, 59

1 files changed, 24 insertions, 0 deletions

diff --git a/haskell/039-interger_right_triangle.hs b/haskell/039-interger_right_triangle.hs
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+++ b/haskell/039-interger_right_triangle.hs
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+-- Integer right triangles
+--
+-- Problem 39
+-- If p is the perimeter of a right angle triangle with integral length sides,
+-- {a,b,c}, there are exactly three solutions for p = 120.
+--
+-- {20,48,52}, {24,45,51}, {30,40,50}
+--
+-- For which value of p ≤ 1000, is the number of solutions maximised?
+
+
+import Data.List(maximumBy)
+
+-- 4m20s stucks
+main = do
+    print (maximumBy (\(_, xs) (_, ys) -> compare (length xs) (length ys)) [
+                (p,
+                [(a, b, p - a - b) | a <- [1..p], b <- [1..(p-a)],
+                validRightTriangle a b (p - a - b)])
+            | p <- [1..1000]
+          ])
+
+validRightTriangle :: Int -> Int -> Int -> Bool
+validRightTriangle a b c = a ^ 2 + b ^ 2 == c ^ 2