我能以某种方式看到haskell试图使用什么模式吗?它适用于较小的示例,但在较大的示例上崩溃,我很难找到它可能是什么情况。
euler18 :: [[Integer]]
euler18 = pathPyr minipyr
pathPyr xss = path [(head xss)] (tail xss)
minipyr = [[3],[7,4],[2,4,6]]
pyramid = [[75], [95,64], [17,47,82], [18,35,87,10], [20,4,82,47,65], [19,1,23,75,3,34], [88,2,77,73,7,63,67], [99,65,4,28,6,16,70,92], [41,41,26,56,83,40,80,70,33], [41,48,72,33,47,32,37,16,94,29], [53,71,44,65,25,43,91,52,97,51,14], [70,11,33,28,77,73,17,78,39,68,17,57], [91,71,52,38,17,14,91,43,58,50,27,29,48], [63,66,4,68,89,53,67,30,73,16,69,87,40,31], [4,62,98,27,23,9,70,98,73,93,38,53,60,4,23]]
path :: [[Integer]] -> [[Integer]] -> [[Integer]]
path xss (ys:[]) = extendpath xss ys
path xss (ys:yss) = path (extendpath xss ys) yss
extendpath :: [[Integer]] -> [Integer] -> [[Integer]]
extendpath (xs:[]) (y1:y2:[]) = [y1:xs,y2:xs]
extendpath (xs:xss) (y1:y2:ys) = [y1:xs,y2:xs] ++ extendpath xss (y2:ys)
输出:
*Main> pathPyr pyramid
[[4,63,91,70,53,41,41,99,88,19,20,18,17,95,75],[62,63,91,70,53,41,41,99,88,19,20,18,17,95,75],[62,66,91,70,53,41,41,99,88,19,20,18,17,95,75],[98,66,91,70,53,41,41,99,88,19,20,18,17,95,75],[98,66,71,70,53,41,41,99,88,19,20,18,17,95,75],[27,66,71,70,53,41,41,99,88,19,20,18,17,95,75],[27,4,71,70,53,41,41,99,88,19,20,18,17,95,75],[23,4,71,70,53,41,41,99,88,19,20,18,17,95,75],[23,4,71,11,53,41,41,99,88,19,20,18,17,95,75],[9,4,71,11,53,41,41,99,88,19,20,18,17,95,75],[9,68,71,11,53,41,41,99,88,19,20,18,17,95,75],[70,68,71,11,53,41,41,99,88,19,20,18,17,95,75],[70,68,52,11,53,41,41,99,88,19,20,18,17,95,75],[98,68,52,11,53,41,41,99,88,19,20,18,17,95,75],[98,89,52,11,53,41,41,99,88,19,20,18,17,95,75],[73,89,52,11,53,41,41,99,88,19,20,18,17,95,75],[73,89,52,11,71,41,41,99,88,19,20,18,17,95,75],[93,89,52,11,71,41,41,99,88,19,20,18,17,95,75],[93,53,52,11,71,41,41,99,88,19,20,18,17,95,75],[38,53,52,11,71,41,41,99,88,19,20,18,17,95,75],[38,53,38,11,71,41,41,99,88,19,20,18,17,95,75],[53,53,38,11,71,41,41,99,88,19,20,18,17,95,75],[53,67,38,11,71,41,41,99,88,19,20,18,17,95,75],[60,67,38,11,71,41,41,99,88,19,20,18,17,95,75],[60,67,38,33,71,41,41,99,88,19,20,18,17,95,75],[4,67,38,33,71,41,41,99,88,19,20,18,17,95,75],[4,30,38,33,71,41,41,99,88,19,20,18,17,95,75],[23,30,38,33,71,41,41,99,88,19,20,18,17,95,75]*** Exception: euler18.hs:(16,1)-(17,72): Non-exhaustive patterns in function Main.extendpath