it is O(n) and complex unnecessary
On Aug 24, 3:58 pm, Ankit Minglani <ankit.mingl...@gmail.com> wrote:
> How about this :
> We use a divide and conquer approach and since the array is sorted.
> We find the middle element and check its value with its immediate left and
> right element .. it must match with anyone of them ..
>
> if it doesnt we have found such a element . and otherwise we divide the
> array again ..
> and then again find the middle element .. to check the same condition ..
>
> This will take O(lg n ) time :)
>
> On Wed, Aug 24, 2011 at 3:45 PM, Venkat <venkataharishan...@gmail.com>wrote:
>
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> > we can solve this with the help of binary search.
>
> > we know N, which is odd(because of one pair missing)
>
> > We divide it array. Let consider your input { 1,1,2,2,2,2,3,3,4,5,5}
>
> > int find_culprit(int[] array, int start, int end)
> > {
> > if(end==start)
> > return -1;
>
> > int mid=((end-start) / 2) + start;
> > if array[mid] == array[mid-1]
> > return find_culprit(mid,end)
> > if(array[mid] == array [mid +1]
> > return find_culprit(start, mid);
> > else
> > return array[mid];
> > }
>
> > Run through:
> > Steps1: find_culprit(array,0,8)
> > mid=4
> > Step 2 : find_culprit(array,4,8))
> > mid=6
> > step 3 : find_culprit(array,6,8))
> > mid=7
> > return array[7]=4 (which dont have pair)
>
> > Run time O(log n+1) = O(log n)
>
> > Please ask if you ve any doubts.....
>
> > Regards
> > Venkat.
>
> > On Aug 24, 2:49 pm, atul purohit <gonewiththe...@gmail.com> wrote:
> > > Hi,
>
> > > A* sorted *integer array contains elements in pairs. All the pairs are
> > > complete except one element whose pair is missing. Find that element.
>
> > > Ex. { 1,1,2,2,2,2,3,3,4,5,5}
> > > result = 5
>
> > > There is a standard solution which returns an XOR of all the elements.
> > But
> > > this needs O(n) time complexity. The person who asked me this question
> > said
> > > that this can be done in < O(n). Maybe we can eliminate some elements.
> > > Anyone knows how to do this?
>
> > > Cheers,
> > > Atul
>
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> --
> The more you sweat in the field, the less you bleed in war."
>
> Ankit Minglani
> NITK Surathkal
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