Simply sort the array and check for a[i]+a[i+1] > a[i+2] for i=0 to n-3.


Sanju
:)



On Sun, Aug 21, 2011 at 7:28 AM, sarvesh saran
<aquarian.thun...@gmail.com>wrote:

>  No idea how to solve the problem except the brute force O(n3) approach.I
> am looking for a better solution than this. Because of O(1) complexity you
> cannot copy and sort the input.
>
>
> A zero-indexed array A consisting of N integers is given. A triplet (P, Q,
> R) is triangular if and
> A[P] + A[Q] > A[R],
> A[Q] + A[R] > A[P],
> A[R] + A[P] > A[Q].
>
> For example, consider array A such that
>
> A[0] = 10 A[1] = 2 A[2] = 5
> A[3] = 1 A[4] = 8 A[5] = 20
> Triplet (0, 2, 4) is triangular.
>
> public int triangle(int[] A)
>
> that, given a zero-indexed array A consisting of N integers, returns 1 if
> there exists a triangular triplet for this array and returns 0 otherwise.
>
> Assume that:
>
> N is an integer within the range [0..100,000];
> each element of array A is an integer within the
> range[-2,147,483,648..2,147,483,647].
> For example, given array A such that
>
> A[0] = 10 A[1] = 2 A[2] = 5
> A[3] = 1 A[4] = 8 A[5] = 20
> the function should return 1, as explained above. Given arrayA such that
>
> A[0] = 10 A[1] = 50 A[2] = 5
> A[3] = 1
> the function should return 0.
> Expected worst-case time complexity: O(n log n)
> Expected worst-case space complexity: O(1)
>
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