Difference between revisions of "Haskell Quiz/PP Pascal/Solution Jethr0"
< Haskell Quiz | PP Pascal
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(+cat) |
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| + | [[Category:Haskell Quiz solutions|PP Pascal]] |
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Example: |
Example: |
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<pre> |
<pre> |
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> pp_pascal 10 |
> pp_pascal 10 |
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| − | 1 |
+ | 1 |
| − | 1 1 |
+ | 1 1 |
| − | 1 2 1 |
+ | 1 2 1 |
| − | 1 3 3 1 |
+ | 1 3 3 1 |
| − | 1 4 6 4 1 |
+ | 1 4 6 4 1 |
| − | 1 5 10 10 5 1 |
+ | 1 5 10 10 5 1 |
| − | 1 6 15 20 15 6 1 |
+ | 1 6 15 20 15 6 1 |
| − | 1 7 21 35 35 21 7 1 |
+ | 1 7 21 35 35 21 7 1 |
| − | 1 8 28 56 70 56 28 8 1 |
+ | 1 8 28 56 70 56 28 8 1 |
| − | 1 9 36 84 126 126 84 36 9 1 |
+ | 1 9 36 84 126 126 84 36 9 1 |
</pre> |
</pre> |
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| Line 17: | Line 18: | ||
Solution: |
Solution: |
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<haskell> |
<haskell> |
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| + | -- also using the pascal triangle function from [[Blow your Mind]] |
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pp_pascal n = unlines . map (center . showp) $ pascal |
pp_pascal n = unlines . map (center . showp) $ pascal |
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where pascal = take n $ iterate (\row -> zipWith (+) ([0] ++ row) (row ++ [0])) [1] |
where pascal = take n $ iterate (\row -> zipWith (+) ([0] ++ row) (row ++ [0])) [1] |
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| − | showp = concat . intersperse " " . map show |
+ | showp = concat . intersperse " " . map show |
len = length . showp $ last pascal |
len = length . showp $ last pascal |
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center s = replicate ((len - (length s)) `div` 2) ' ' ++ s |
center s = replicate ((len - (length s)) `div` 2) ' ' ++ s |
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Latest revision as of 11:12, 13 January 2007
Example:
> pp_pascal 10
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
1 8 28 56 70 56 28 8 1
1 9 36 84 126 126 84 36 9 1
Solution:
-- also using the pascal triangle function from [[Blow your Mind]]
pp_pascal n = unlines . map (center . showp) $ pascal
where pascal = take n $ iterate (\row -> zipWith (+) ([0] ++ row) (row ++ [0])) [1]
showp = concat . intersperse " " . map show
len = length . showp $ last pascal
center s = replicate ((len - (length s)) `div` 2) ' ' ++ s