Bill Kelly wrote: > 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 Thanks. Given I have the 0 and 1 array, Replacing all the 0s with "~", and replacing all the 1s with the right letters, I think it should work. -- Posted via http://www.ruby-forum.com/.