如何创建与特定数字相加的数字列表 [英] How to create a list of numbers that add up to a specific number

问题描述

我需要帮助在 Prolog 中编写一个谓词，该谓词将一个数字作为输入，返回一个列表列表，其中的数字相加.

I need some help writing a predicate in Prolog that, given a number as input, returns a list of lists with numbers that add up to it.

让我们调用谓词 addUpList/2，它应该是这样工作的:

Let's call the predicate addUpList/2, it should work like this:

?- addUpList(3,P).
P = [[1,2], [2,1], [1,1,1]].       % expected result

我很难弄清楚这一点，我开始认为这是不可能的.有任何想法吗?提前致谢.

I'm having so much trouble figuring this out I'm beginning to think it's impossible. Any ideas? Thanks in advance.

推荐答案

试试这个:

condense([], Rs, Rs).
condense([X|Xs], Ys, Zs) :-
    condense(Xs, [X|Ys], Zs).
condense([X, Y|Xs], Ys, Zs) :-
    Z is X + Y,
    condense([Z|Xs], Ys, Zs).

condense(Xs, Rs) :-
    condense(Xs, [], Rs).

expand(0, []).
expand(N, [1|Ns]) :-
    N > 0,
    N1 is N - 1,
    expand(N1, Ns).

addUpList(N, Zs) :-
    expand(N, Xs),
    findall(Ys, condense(Xs, Ys), Zs).

让我知道我得到了什么分数.:-)

Let me know what marks I get. :-)

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