From: Bill Kelly <billk@...>
Date: 2010-01-05T14:54:03+09:00
Subject: Re: How to generate a collection?

Nanyang Zhan wrote:
> Given any four letter word, for example: "card"
> Replace one to three letters with "~",
> How can I get the result collection ( ["~ard", "c~rd", ..., "~~r~",
> "~~~d"])?

One idea:

irb> 1.upto(14) {|i| printf("%04b\n", i)}
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110


Regards,

Bill