I think you have not read the question carefully. Please read it again and try to ans for small values of n,k first. for k=1, answer will be always 1.
On Mon, Jun 20, 2011 at 6:31 PM, saurabh singh <[email protected]> wrote: > O.K can anyone suggest the combinatorial solution.I thought it this way- > Assume k chairs as one chair.Now no. of ways arranging these chairs would > be ((n-k+1)-1)! and the number of ways of arranging the k chairs would be > k!. > So the no. of ways of arranging the chairs so that they are always together > becomes..(n-1)!-(n-k)!*(k)!? > Where was I wrong in the approach?Please correct me, > > > On Mon, Jun 20, 2011 at 5:36 PM, RITESH SRIVASTAV < > [email protected]> wrote: > >> @Saurabh >> Your formula is incorrect. >> for input : 5 2 >> the answer should be 5 but your program gives 12 as output. >> >> On Jun 19, 11:35 pm, abc abc <[email protected]> wrote: >> > @above Better you ask it on spoj forum >> > >> > On Sun, Jun 19, 2011 at 7:27 PM, saurabh singh <[email protected]> >> wrote: >> > > I am getting WA for this problem.I dont know whether its case of >> overflow >> > > or I have come up with a wrong formula, >> > >https://www.spoj.pl/problems/CHAIR/ >> > > I am coding in python so I dont think there is probblem of overflow. >> > >> > > def f(n): >> > > if n<0: >> > > return 0 >> > > if n==0: >> > > return 1 >> > > i=n >> > > prod=1 >> > > while i>0 : >> > > prod*=i >> > > i-=1 >> > > return prod >> > > n=input() >> > > k=input() >> > > if k==1: >> > > print n >> > > elif 2*k>n: >> > > print 0 >> > > else : >> > > x=f(n-1) >> > > y=f(n-k)*f(k) >> > > print (x-y)%1000000003 >> > >> > > -- >> > > Saurabh Singh >> > > B.Tech (Computer Science) >> > > MNNIT ALLAHABAD >> > >> > > -- >> > > You received this message because you are subscribed to the Google >> Groups >> > > "Algorithm Geeks" 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/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 [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/algogeeks?hl=en. >> >> > > > -- > Saurabh Singh > B.Tech (Computer Science) > MNNIT ALLAHABAD > > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" 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/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 [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
