Successive prime differences: Difference between revisions

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findPrimes :: [Int] -> [[Int]] -> Result

findPrimes [] _ = []

findPrimes primes diffs = loopDiffs diffs <> findPrimes (tail primes) diffs

where

~~where~~ loopDiffs [] = []

loopDiffs [] = []

loopDiffs (d:ds)

loopDiffs (d : ds)

| subs successive == d = (show d, successive) : loopDiffs ds

| ~~otherwise~~ = loopDiffs ds

| subs successive == d = (show d, successive) : loopDiffs ds

~~where~~ ~~successive~~ = ~~take~~ ~~(length~~ d + 1) ~~primes~~

| otherwise = loopDiffs ds

where

subs = map (uncurry (-)) . init . tail . (\xs -> zip (xs <> [0]) (0 : xs))

successive = take (length d + 1) primes

subs = map (uncurry (-)) . init . tail . (\xs -> zip (xs <> [0]) (0 : xs))

showGroup :: Result -> String -> IO ()

showGroup result diffs = do

putStrLn $ "Differences of " ++ diffs ++ ": " ++ show (length groups)

putStrLn

putStrLn $ "First: " ++ firstGroup groups ++ "\nLast: " ++ lastGroup groups ++ "\n"

$ "First: "

~~where~~ ~~groups~~ = foldr (\(a, b) c -> if a == diffs then b : c else c) [] result

firstGroup ~~= show . head~~

++ firstGroup groups

++ "\nLast: "

lastGroup ~~= show . last~~

++ lastGroup groups

++ "\n"

where

groups = foldr (\(a, b) c -> if a == diffs then b : c else c) [] result

firstGroup = show . head

lastGroup = show . last

main :: IO ()

main = mapM_ (showGroup result . show) diffs

where

~~where~~ (diffs, result) = groups [[2], [1], [2,2], [2,4], [4,2], [6,4,2]]

(diffs, result) = groups [[2], [1], [2, 2], [2, 4], [4, 2], [6, 4, 2]]

groups diffs = (diffs, findPrimes (takeWhile (<1_000_000) primes) diffs)</lang>

groups diffs = (diffs, findPrimes (takeWhile (< 1_000_000) primes) diffs)</lang>

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