Given any number $N$ find a positive integer $k$ such that: $N + 12 k$ is a square.

And the second case when we add an additional constraint that $k$ must be as small as possible.


1 Answer 1


What’s the solution for N = 12m + 2, 3, 5, 6, 7, 8, 10, 11?

You can prove that no solution exists or find a solution in O(log N). You can find the smallest solution in O(log N log log N) or more precisely in the time it takes to multiply numbers of log N digits.


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