ruby - 如何计算两个字符串共有的字符数？

Question

如何计算两个字符串之间的字符交集？

例如(假设我们有一个名为 String.intersection 的方法):

"abc".intersection("ab") = 2
"hello".intersection("hallo") = 4

好的，男孩女孩们，感谢你们的大量反馈。更多示例:

"aaa".intersection("a") = 1
"foo".intersection("bar") = 0
"abc".intersection("bc") = 2
"abc".intersection("ac") = 2
"abba".intersection("aa") = 2

一些补充说明:维基百科定义 intersection如下:

Intersection of the sets A and B, denoted A ∩ B, is the set of all objects that are members of both A and B. The intersection of {1, 2, 3} and {2, 3, 4} is the set {2, 3}

Answer 1

使用String#count :

irb(main):001:0> "hello".count("hallo")
=> 4
irb(main):002:0> "abc".count("ab")
=> 2