@Paul Thanks for answering for me
@Eagle Glad I could help =) On May 9, 3:10 pm, Eagle <[email protected]> wrote: > @Pedro, > > In your last two steps, > > > E[n=3] = 2 + 1/3 * E[n=3] > > > E[n=3] = 3 > > there is something wrong. How are you eliminating E[n=3] on the right > hand side of the equation? > > Eagle > > On May 9, 12:28 am, Pedro Osório <[email protected]> wrote: > > > > > > > > > Hi Ricardo, > > > For your example regarding 3, you have the following possibilities: > > > 1 2 3 - perfect > > 1 3 2 - one correct > > 2 1 3 - one correct > > 2 3 1 - wrong > > 3 1 2 - wrong > > 3 2 1 - one correct > > > As you can see, if goro hits without holding anything, 1/6 of the time > > it will be sorted, 1/2 of the time there will be 2 out of place and > > 1/3 of the time there will be 3 out of place. > > > This means that: > > > E[n=3] = 1 + (1/6 * 0 + 1/2 * E[n=2] + 1/3 * E[n=3]) > > > As you have shown, E[n=2] = 2, so: > > > E[n=3] = 2 + 1/3 * E[n=3] > > > E[n=3] = 3 > > > On May 8, 7:57 pm, werneckpaiva <[email protected]> wrote: > > > > I read too and it doesn't make any sense for me. > > > > I understand that this is a geometric distribution where if P(X)=p so > > > E(X)=1/p. So, if you have 2 numbers unsorted and Goro hits the table, > > > there is 0.5% chance to stay in the same position and 0.5% chance to > > > swap positions. But, if you have 3 unsorted elements, there are 6 > > > different permutations, so, P(X)=1/6 and the E(X)=6. My solution is > > > hold 1 number, swap the other 2; hold the sorted element and swap the > > > other 2 remaining, so 2 + 2 = 4 hits > > > > 3 1 2 > > > 1 3 2 > > > 1 2 3 > > > > But this doesn't seem to be the correct answer. The developers > > > solutions say that for 3 unsorted numbers needs only 3 hits. Anyone > > > knows how to explain that? > > > > Regards, > > > > Ricardo > > > > On May 7, 8:24 pm, SwiftCoder <[email protected]> wrote: > > > > > I looked at some of the solutions, as per that umber of hits are same > > > > as the count of numbers which are not at their correct sorted > > > > position. Is that so? -- You received this message because you are subscribed to the Google Groups "google-codejam" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-code?hl=en.
