@Ankit..your algm is O(n)...you should split the problem size to n/2 at
every stage...rather you are again computing both the subarrays..
Here is the correct code...
int BsearchElemEqualIndex (int *a, int start, int end)
{
int mid = (((end - start) >> 1) + start);
if (a[mid] == mid)
return a[mid];
else if (a[mid] != mid)
{
if (mid == start || mid == end)
{
return -1;
}
else
{
if(a[mid] < mid )
BsearchElemEqualIndex (a, start, mid);
BsearchElemEqualIndex (a, mid + 1, end);
}
}
}
int _tmain(int argc, _TCHAR* argv[])
{
int a[SIZE] = {5,9,3,8,1,2,6,7};
int x = BsearchElemEqualIndex (a, 0, SIZE);
printf ("%d", x);
system ("PAUSE");
return 0;
}
On Thu, Mar 3, 2011 at 7:20 PM, jagannath prasad das <jpdasi...@gmail.com>wrote:
> @ankit sinha:i dont think the algo u wrote is o(logn).....its o(N) i guess
>
>
> On Thu, Mar 3, 2011 at 7:05 PM, Ankit Sinha <akki12...@gmail.com> wrote:
>
>> @sukhmeet, as per the question, there is a unique value which satisfy
>> a[i] = i in the array and written code captures that only. Else we
>> need to modify if we are interested in all such values which statisfy
>> the said condition. And also in that case looping around bsearch will
>> not be a good idea.. it will be better to go for simple loop in o(n)
>> time as every time mid calculation is also costly. I agreed to Arpit
>> view point and accordingly did coding as preetika needed as per arpit
>> comments.
>>
>> Cheers!!
>> Ankit
>>
>> On Thu, Mar 3, 2011 at 6:53 PM, sukhmeet singh <sukhmeet2...@gmail.com>
>> wrote:
>> > what should be the answer for this:
>> > if A={0,1,2,4,5}
>> > 0 or 1 or 2
>> > On Thu, Mar 3, 2011 at 6:26 PM, Ankit Sinha <akki12...@gmail.com>
>> wrote:
>> >>
>> >> Hi,
>> >>
>> >> Here is the code to do this using Bsearch in o(logn) time.
>> >>
>> >> int BsearchElemEqualIndex (int *a, int start, int end)
>> >> {
>> >> int mid = (((end - start) >> 1) + start);
>> >> if (a[mid] == mid)
>> >> return a[mid];
>> >> else if (a[mid] != mid)
>> >> {
>> >> if (mid == start || mid == end)
>> >> {
>> >> return -1;
>> >> }
>> >> else
>> >> {
>> >> BsearchElemEqualIndex (a, start, mid);
>> >> BsearchElemEqualIndex (a, mid + 1, end);
>> >> }
>> >> }
>> >> }
>> >>
>> >> int _tmain(int argc, _TCHAR* argv[])
>> >> {
>> >> int a[SIZE] = {5,9,3,8,1,2,6,7};
>> >> int x = BsearchElemEqualIndex (a, 0, SIZE);
>> >> printf ("%d", x);
>> >> system ("PAUSE");
>> >> return 0;
>> >> }
>> >>
>> >> Cheers,
>> >> Ankit!!!
>> >>
>> >> On Thu, Mar 3, 2011 at 11:04 AM, Param10k <paramesh...@gmail.com>
>> wrote:
>> >> > There is a sorted array and you have to write a fn to find a number
>> in
>> >> > the array which satisfies
>> >> >
>> >> > A[i] = i ; where A is the array and i is the index...
>> >> >
>> >> > - Param
>> >> > http://teknotron-param.blogspot.com/
>> >> >
>> >> > --
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--
S.Nishaanth,
Computer Science and engineering,
IIT Madras.
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