ruby-on-rails – 笛卡尔积ruby
发布时间:2020-12-16 21:17:26 所属栏目:百科 来源:网络整理
导读:class CartesianProductinclude Enumerable# your code hereend#Examples of usec = CartesianProduct.new([:a,:b],[4,5])c.each { |elt| puts elt.inspect }# [:a,4]# [:a,5]# [:b,4]# [:b,5]c = CartesianProduct.new([:a,[])c.each { |elt| puts elt.insp
class CartesianProduct include Enumerable # your code here end #Examples of use c = CartesianProduct.new([:a,:b],[4,5]) c.each { |elt| puts elt.inspect } # [:a,4] # [:a,5] # [:b,4] # [:b,5] c = CartesianProduct.new([:a,[]) c.each { |elt| puts elt.inspect } # (nothing printed since Cartesian product # of anything with an empty collection is empty) 我是ruby的新手.我理解如何定义笛卡儿积的实例方法,但我对此毫无头绪.我应该如何构造类对象以满足要求. 解决方法
我不会使用一个类,但保持问题的结构,我写道:
class CartesianProduct include Enumerable def initialize(xs,ys) @xs = xs @ys = ys end def each return to_enum unless block_given? @xs.each do |x| @ys.each { |y| yield [x,y] } end end end 相反,如果懒惰很重要,我只需编写xs.product(ys)或构建我自己的Array#lazy_product(参见本ticket). (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |