[英]QuickSort applied to a list of tuples (Int,[Int]) in Haskell
下午好,
我是 Haskell 的新手,我正在嘗試調整我制作的 QuickSort 算法,以使用元組列表對“Int”列表進行排序,但我完全不知道如何將尾部綁定到“a”讓它按照我的需要工作,或者是否可以重用代碼。 這是我用來對“Int”列表進行排序的內容:
quickSort :: Ord a => [a] -> [a]
quickSort [] = []
quickSort (x:xs) =
let smallSort = quickSort [a | a <- xs, a < x]
biggerSort = quickSort [a | a <- xs, a > x]
in smallSort ++ [x] ++ biggerSort
這是我試圖用它做的,所以我可以對元組列表(Int,[Int])進行排序。 我想按元組的第一個元素對元組進行排序,所以如果我得到一個類似 [(2,[1]),(1,[]),(3,[2,1])] 的列表,它會返回這個[(1,[]),(2,[1]), (3,[2,1])]。
quickSortTuplas ((x,(ks)) : []) = [(x,(ks))]
quickSortTuplas ((x,(ks)):ps) =
let smallSort = quickSort [a | a <- ps, a < x]
biggerSort = quickSort [a | a <- ps, a > x]
in smallSort ++ [(x,(ks))] ++ biggerSort
如果我嘗試加載它,我會收到以下錯誤:
Occurs check: cannot construct the infinite type: a ~ (a, [a1])
* In the second argument of `(>)', namely `x'
In the expression: a > x
In a stmt of a list comprehension: a > x
* Relevant bindings include
a :: (a, [a1]) (bound at reNuevoHaskell.hs:60:37)
biggerSort :: [(a, [a1])] (bound at reNuevoHaskell.hs:60:9)
ps :: [(a, [a1])] (bound at reNuevoHaskell.hs:58:27)
ks :: [a1] (bound at reNuevoHaskell.hs:58:22)
x :: a (bound at reNuevoHaskell.hs:58:19)
quickSortTuplas :: [(a, [a1])] -> [(a, [a1])]
(bound at reNuevoHaskell.hs:57:1)
非常感謝您能給我的任何見解。
表達式中的通知[a | a <- ps, a < x]
[a | a <- ps, a < x]
。 a
是一個元組,而x
是一個Int
。 因此a < x
沒有意義。 無論如何,因為您的quicksort
適用於Ord a
,您也可以使用它對元組列表進行排序。 試試看`!
quickSort :: Ord a => [a] -> [a]
quickSort [] = []
quickSort (x:xs) =
let smallSort = quickSort [a | a <- xs, a < x]
biggerSort = quickSort [a | a <- xs, a > x]
in smallSort ++ [x] ++ biggerSort
main = print $ quickSort [(1,[2,3,4]) , (0, [4,5,6]), (2,[1,2,3])] -- This works fine
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.