From: Gavin Kistner <redmine@...>
Date: 2010-07-17T04:52:28+09:00
Subject: [ruby-core:31318] [Bug #3581] Array#combination enumerator ends iteration early

Bug #3581: Array#combination enumerator ends iteration early
http://redmine.ruby-lang.org/issues/show/3581

Author: Gavin Kistner
Status: Open, Priority: Normal
ruby -v: ruby 1.9.1p243 (2009-07-16 revision 24175) [i386-mingw32]

C:\>type big_combination.rb 
count = 0 
combo = nil 
(1..166).to_a.combination(5).each do |c| 
  count+= 1; combo = c 
end 
p count, combo 

C:\>ruby -v big_combination.rb 
ruby 1.9.1p243 (2009-07-16 revision 24175) [i386-mingw32] 
129462338 
[5, 34, 54, 73, 81] 

The same (incorrect) results are witnessed using 1.9.1p378 on Ubuntu.

The expected result should be:
   988455798 
   [162, 163, 164, 165, 166]

As noted in a ruby-talk thread[1], the correct results were seen on 1.9.1p129

Note that changing "166" to "141" in the above code instead results in the RangeError "in `combination': too big for combination". Perhaps this is the same issue as bug #3089 [ruby-core:29240].

[1] http://groups.google.com/group/comp.lang.ruby/browse_frm/thread/c558332ff0a053ad/67e87e76d289889e#67e87e76d289889e


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