2016-01-23 66 views
3

我需要将多个列表与常用元素合并为一个。我应该在清单内做到这一点。在Haskell中合并类似的列表清单

例如:

INPUT: [[1,2,3],[5,6],[8,3,11],[4,9,1]]

MY输出: [[1,2,3,8,3,11,1,2,3,4,9,1],[]]

需要的输出: [[1,2,3 ,8,11,9],[5,6]]

另一个例子:

INPUT: [[4],[0],[7,10],[6],[6]]

MY输出: [[6,6],[]]

OUTPUT: [[4],[0],[7,10],[6]]

我的代码:

mergeAllLists :: [[Integer]] -> [[Integer]] 
mergeAllLists (x:[]) = [x] 
mergeAllLists (x:[]:y) = [x] 
mergeAllLists (x:y:[]:_) = mergeOneToAll_ x [y] 
mergeAllLists (x:xs) = mergeAllLists (mergeOneToAll x xs) 

mergeOneToAll :: [Integer] -> [[Integer]] -> [[Integer]] 
mergeOneToAll _ [] = [[]] 
mergeOneToAll list (y:list_of_list) = (mergeLists list y) : (mergeOneToAll list list_of_list) 
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列表中是否包含数字的两次出现?如果它们是重要的?我的意思是:如果输入是[[1,1,2],[2,3]],你会介意结果是[[1,2,3]]而不是'[[1,1 1,2,3]]'? – Bakuriu

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是的,我可以删除重复以后 – dandycomp

回答

2
mergeAllLists :: [[Integer]] -> [[Integer]] 
mergeAllLists = foldl mergeOneToAll [] 

mergeOneToAll :: [[Integer]] -> [Integer] -> [[Integer]] 
mergeOneToAll [] xs = [xs] 
mergeOneToAll (as:acc) xs = 
    if null $ intersect xs as then 
    as : mergeOneToAll acc xs 
    else 
    (as ++ xs) : acc 

我t虽然不是很有效(不是尾递归)。让我知道它是否需要更高效,我会尝试改进它。

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Thx很多,它的工作 – dandycomp