if you know the range of the numbers don't you just have to create and array (of length k in your example) then iterate over the array and increment the corresponding element in the other array.
Ie, int[] arrayValues = some array of a known range int[] arrayLookup = int[min_in_range - max_in_range + 1] foreach(i in arrayValues) if(arrayLookup[i] > 0) then found else arrayLookup[i]++ Of course range could be prohibitively large (still constant though if you know the range before hand). On 8/17/07, Vaibhav Jain <[EMAIL PROTECTED]> wrote: > if u know the range of values stored in array then > let me assume values 1 to k then u can calculate sum of numbers stored in > array in O(n) complexity. > after that apply formula > > duplicate value= [k*(k+1)]/2 - sum of numbers stored in array > > it will take O(1) constant time so total complexity becomes only O(n). > > it can be one solution to your problem but if the range is unknown for > values then > is there any solution to come in O(n)??? > > > > On 8/16/07, dsha <[EMAIL PROTECTED]> wrote: > > > > Hi there, > > > > I'm interested in the following problem: there is an array of integers > > that contains each element only once except for one element that > > occurs exactly twice. Is there a way to find this element faster than > > O(n*log n) and with constant extra memory? If no, how can I prove it? > > > > Thanks in advance for ideas. > > > > > > > > > > > > > > -- > Vaibhav Jain > > > > --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/algogeeks -~----------~----~----~----~------~----~------~--~---