can u explain how is this number reached at? (2n)!/((n+1)!(n!)) Best Regards Ashish Goel "Think positive and find fuel in failure" +919985813081 +919966006652
On Thu, Aug 5, 2010 at 12:53 PM, umesh kewat <[email protected]> wrote: > Calculate the number of string can be formed by this formula in one > statement.. > > for cross check the result is > > 2N!/((N+1)! * N!).... where is number of A or B in string > > > > > On Thu, Aug 5, 2010 at 8:54 AM, Ashish Goel <[email protected]> wrote: > >> >>> >>> void dyckWords(int index, int open, int close) >>> { >>> static int dyck=0; >>> if (index == 2 *n) >>> { >>> printf("%s\n", out); >>> return ; >>> } >>> >>> out[index] = '('; //or A >>> if ((open + 1) <= n && open >= close) >>> >>> >>> >>> >>> >>> { >>> dyckWords(index + 1, open + 1, close); >>> } >>> out[index] = ')';//or B >>> >>> if ((close + 1) <= n && open >= close) >>> { >>> dyckWords(index + 1, open, close + 1); >>> >>> >>> } >>> } >>> >>> Best Regards >>> Ashish Goel >>> "Think positive and find fuel in failure" >>> +919985813081 >>> +919966006652 >>> >>> >>> On Mon, Jul 19, 2010 at 1:25 AM, Amir hossein Shahriari < >>> [email protected]> wrote: >>> >>>> @ashish: AAA is the prefix of the string and it is valid as a prefix and >>>> it's only used for strings with length >= 6 (where it is a valid prefix) >>>> actually only dp[i][j] where i==j counts the number of such strings and >>>> otherwise there is no string where i!=j and it that case dp[i][j] counts >>>> the >>>> number of valid prefixes for string >>>> dp[0][0]=1 does satisfy both properties because 0=0 so the number of As >>>> & Bs are the same >>>> the logic behind n/2 is that if the length of the string is n this means >>>> that it has n/2 As and n/2 Bs (n must be even) >>>> the dp for n=4 doesn't look like that! this is how it looks (i just >>>> compiled the code and checked values of dp): >>>> 1 0 0 >>>> 1 1 0 >>>> 1 2 2 >>>> so dp[2][2]=2 which means the number of strings with 2 As and 2 Bs is 2 >>>> >>>> >>>> -- >>>> 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]<algogeeks%[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]<algogeeks%[email protected]> >> . >> For more options, visit this group at >> http://groups.google.com/group/algogeeks?hl=en. >> > > > > -- > Thanks & Regards > > Umesh kewat > > > > -- > 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]<algogeeks%[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.
