http://www.acmicpc.net/problem/1004

gistfile1.hs

type Point = (Float, Float)
data Orbit = Orbit Point Float
data TestCase = TestCase Point Point [Orbit]

-- Input

readFloats :: IO [Float]
readFloats = do
    line <- getLine
    return (map read (words line))

readInt :: IO Int
readInt = getLine >>= return . read

readOrbit = do
    orbit <- readFloats
    let cx:cy:r:_ = orbit
    return (Orbit (cx, cy) r)

readTestCase = do
    points <- readFloats
    let x1:y1:x2:y2:_ = points
    n <- readInt
    orbits <- sequence (replicate n readOrbit)
    return (TestCase (x1, y1) (x2, y2) orbits)

-- Process

distance :: Point -> Point -> Float
distance (x1, y1) (x2, y2) = sqrt ((x1 - x2) ^ 2 + (y1 - y2) ^ 2)

contains :: Orbit -> Point -> Bool
contains (Orbit c r) p = (distance c p) <= r

countIf pred xs = length (filter pred xs)

evaluate (TestCase from to orbits) =
    countIf (\x -> (contains x from) /= (contains x to)) orbits

-- Output

main = do
    n <- readInt
    testCases <- sequence (replicate n readTestCase)
    print (map evaluate testCases)