Prolog中的偶数和，奇数乘积 [英] Sum of even, product of odd numbers in Prolog

问题描述

我有一个数字列表，我需要计算该列表的偶数和同一列表的奇数的乘积之和.我是Prolog的新手，到目前为止，我的搜索未成功.有人可以帮我解决吗?

I have a list of numbers, I need to calculate the sum of the even numbers of the list and the product of the odd numbers of the same list. I'm new in Prolog, and my searches so far weren't successful. Can anyone help me solve it ?

l_odd_even([]). 
l_odd_even([H|T], Odd, [H|Etail]) :-
    H rem 2 =:=0,
    split(T, Odd, Etail). 
l_odd_even([H|T], [H|Otail], Even) :-
    H rem 2 =:=1,
    split(T, Otail, Even).

推荐答案

以下是列表中偶数之和的建议:

Here is a suggestion for the sum of the even numbers from a list:

even(X) :- 
  Y is mod(X,2),       % using "is" to evaluate to number
  Y =:= 0.

odd(X) :-              % using even
  Y is X + 1,
  even(Y).

sum_even(0, []).       % empty list has zero sum
sum_even(X, [H|T]) :- 
  even(H),
  sum_even(Y, T), 
  X is Y+H.
sum_even(X, [H|T]) :- 
  odd(H),
  sum_even(X, T).      % ignore the odd numbers

注意:我的Prolog已被氧化，因此可能有更好的解决方案. :-)

Note: My Prolog has oxidized, so there might be better solutions. :-)

注意:圣牛！ Prolog似乎不支持语法突出显示(请参见在这里)，所以我使用了Erlang语法. 哈，确实有效. :-)

Note: Holy cow! There seems to be no Prolog support for syntax highlighting (see here), so I used Erlang syntax. Ha, it really works. :-)

在GNU Prolog中运行一些查询，我得到:

Running some queries in GNU Prolog, I get:

| ?- sum_even(X,[]).    
X = 0 ?     
yes

| ?- sum_even(X,[2]).   
X = 2 ? 
yes

| ?- sum_even(X,[3]).    
X = 0 ? 
yes

| ?- sum_even(X,[5,4,3,2,1,0]).    
X = 6 ? 
yes

此处应用的想法应使您能够提出所需的产品.

The ideas applied here should enable you to come up with the needed product.

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