Difference between revisions of "Talk:Euler problems/121 to 130"
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Just another thought: as you have solutions handy for most problems, couldn't those guarding these pages do the copyvio checking themselves? |
Just another thought: as you have solutions handy for most problems, couldn't those guarding these pages do the copyvio checking themselves? |
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[[User: hk|hk]] |
[[User: hk|hk]] |
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| + | If it was posted by glguy, I'm willing to bet he's okay with it being here, but I'll check with him. |
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| + | [[User:CaleGibbard|CaleGibbard]] 14:57, 25 February 2008 (UTC) |
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Revision as of 14:57, 25 February 2008
On the Project Euler Forum I found the following solution for Problem 127, posted there by glguy.
main = print $ solve 99999
rad x = fromIntegral $ product $ map fst $ primePowerFactors $ fromIntegral x
solve :: Int -> Int solve n = sum [ c | (rc,c) <- invrads
, 2 * rc < c
, (ra, a) <- takeWhile (\(a,_)->(c > 2*rc*a)) invrads
, a < c `div` 2
, gcd ra rc == 1
, ra * rads ! (c - a) < c `div` rc]
where
rads :: UArray Int Int
rads = listArray (1,n) $ map rad [1..n]
invrads = sort $ map (\(a,b) -> (b, a)) $ assocs rads
Would responsible people be so kind as to check copyvio for this one? As far as I'm concerned it is. Just another thought: as you have solutions handy for most problems, couldn't those guarding these pages do the copyvio checking themselves? hk
If it was posted by glguy, I'm willing to bet he's okay with it being here, but I'll check with him. CaleGibbard 14:57, 25 February 2008 (UTC)