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Task/Closest-pair-problem/Haskell/closest-pair-problem-1.hs

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+import Data.List
+import System.Random
+import Control.Monad
+import Control.Arrow
+import Data.Ord
+
+vecLeng [[a,b],[p,q]] = sqrt $ (a-p)^2+(b-q)^2
+
+findClosestPair =  foldl1' ((minimumBy (comparing vecLeng). ). (. return). (:)) .
+                   concatMap (\(x:xs) -> map ((x:).return) xs) . init . tails
+
+testCP = do
+    g <- newStdGen
+    let pts :: [[Double]]
+        pts = take 1000. unfoldr (Just. splitAt 2) $ randomRs(-1,1) g
+    print . (id &&& vecLeng ) . findClosestPair $ pts