Say you have a^2 + b^2 + c^2 = d.
Keep a sorted list of all possible a^2 + b ^ 2 ... this would take n^2 time to generate and n^2 log n to sort. Now loop over all possible 'd' and 'c' and compute d - c ^ 2. Use binary search to determine whether that number is in the list ... if it is then 'd' is a number which CAN be represented otherwise try for the next 'c'.
There might be a better solution ... still thinking
-Dhyanesh
On 10/31/06, Karthik Rathinavelu <
[EMAIL PROTECTED]> wrote:
Question: Given n, find the numbers in the range of 0...n which CAN'T be represented in the form of sum of squares of 3 non-negative numbers.
If anyone could possibly give a solution better than O(n^3), it will be good.
Thanks,
R.Karthik
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