This problem is similar to Coupan collector problem. http://en.wikipedia.org/wiki/Coupon_collector%27s_problem
In your case the answer is [image: For N-Dice ; \newline \sum_{i=1}^{N} N/i \newline for\; N =~2 ; \newline \sum_{i=1}^{2} 2/i = 2/1 + 2/2 = 3 \newline] Hope it helps! -- Amitesh On Sat, Jun 16, 2012 at 5:18 PM, Gaurav Popli <gpgaurav.n...@gmail.com>wrote: > What is the expected number of throws of his die while it has N sides > so that each number is rolled at least once? > e.g > for n=2 ans 3.00 > n=12 ans is 37.24... > i refrd to expectation tutuorial at > http://www.codechef.com/wiki/tutorial-expectation but still couldnt > get the logic... > > any help? > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to algogeeks@googlegroups.com. > To unsubscribe from this group, send email to > algogeeks+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.