Data commit

Task/Stern-Brocot-sequence/Miranda/stern-brocot-sequence.miranda

@@ -0,0 +1,35 @@
+main :: [sys_message]
+main = [Stdout (lay
+         ["First 15: " ++ show first15,
+          "Indices of first 1..10: " ++ show idx10,
+          "Index of first 100: " ++ show idx100,
+          "The GCDs of the first 1000 pairs are all 1: " ++ show allgcd])]
+
+first15 :: [num]
+first15 = take 15 stern
+
+idx10 :: [num]
+idx10 = [find num stern | num<-[1..10]]
+
+idx100 :: num
+idx100 = find 100 stern
+
+allgcd :: bool
+allgcd = and [gcd a b = 1 | (a, b) <- take 1000 (zip2 stern (tl stern))]
+
+
+|| Stern-Brocot sequence
+stern :: [num]
+stern = 1 : 1 : concat (map consider (zip2 stern (tl stern)))
+        where consider (prev,item) = [prev + item, item]
+
+|| Supporting functions
+gcd :: num->num->num
+gcd a 0 = a
+gcd a b = gcd b (a mod b)
+
+find :: *->[*]->num
+find item = find' 1
+            where find' idx []     = 0
+                  find' idx (a:as) = idx, if a = item
+                                   = find' (idx + 1) as, otherwise