after getting one number cant u subtract from S?? On Tue, Aug 4, 2009 at 5:53 PM, Anil C R <[email protected]> wrote:
> Pretty! :) > > Channa Bankapur wrote: > > Elegant.. I think it can't be better than this. Identifying that each > > of them are on different sides of S/2 was the key! > > > > > > On Tue, Aug 4, 2009 at 10:05 AM, Prunthaban Kanthakumar > > <[email protected] <mailto:[email protected]>> wrote: > > > > Here is the right answer: > > > > Find the sum of missing numbers. Call it S (this is a easy to do). > > Now the two missing numbers are such that one is <=S/2 and the > > other is > S/2 > > Have two variables S1 and S2, traverse the array and add > > everything <= S/2 to S1 and > S/2 to S2. > > Now > > First number = (Sum of numbers from 1 to S/2) - S1 > > Second Number = (Sum of numbers from [S/2 + 1] to n+2) - S2 > > > > O(n) time and O(1) space. > > > > > > On Tue, Aug 4, 2009 at 3:28 AM, Karthik Singaram Lakshmanan > > <[email protected] <mailto:[email protected]>> > wrote: > > > > > > well..will this work? > > > > x + y = SUM(1:N+2) - SUM(array) = a > > x^2 + y^2 = SUM(1^2:(N+2)^2) - SUM(array.^2) = b > > so (a^2 - b) = 2xy > > > > so xy = (a^2-b)/2 = k (say) > > > > now, > > > > x + (k/x) = a > > > > x^2 + k = ax > > (x, y) = (a +/- sqrt(a^2-4k))/2 > > > > I may not have written the equations correctly (need coffee !!!) > > but you get the general idea... > > solve a quadratic equation to solve for (x+y) = a and (x^2 + > > y^2) = b > > > > - Karthik > > > > > > > > > > > > > > > > > > > > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
