To Mr. B
how will you find median in O(n) time? please elaborate.
On Wednesday, July 11, 2012 4:01:43 AM UTC+5:30, Mr.B wrote:
>
> I found a similar solution looking somewhere else.
>
> The solution for this problem is:
> a. There can be atmost 3 elements (only 3 distinct elements with each
> repeating n/3 times) -- check for this and done. -- O(n) time.
> b. There can be atmost 2 elements if not above case.
>
> 1. Find the median of the input. O(N)
> 2. Check if median element is repeated N/3 times or more -- O(n) - *{mark
> for output if yes}*
> 3. partition the array based on median found above. - O(n) -- {partition
> is single step in quicksort}
> 4. find median in left partition from (3). - O(n)
> 5. check if median element is repeared n/3 times or more - O(n) *{mark
> for output if yes}*
> 6. find median in right partition from (3). - O(n)
> 7. check if median element is repeared n/3 times or more - O(n) *{mark
> for output if yes}*
>
> its 7*O(N) => O(N) solution. Constant space.
>
> we need not check further down or recursively. {why? reason it.. its
> simple}
>
>
> On Wednesday, 27 June 2012 18:35:12 UTC-4, Navin Kumar wrote:
>>
>>
>> Design an algorithm that, given a list of n elements in an array, finds
>> all the elements that appear more than n/3 times in the list. The algorithm
>> should run in linear time
>>
>> ( n >=0 ).
>>
>> You are expected to use comparisons and achieve linear time. No
>> hashing/excessive space/ and don't use standard linear time deterministic
>> selection algo.
>>
>>
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