I found several questions regarding the POLYEVAL problem at CS.stackexchange.

- http://cs.stackexchange.com/questions/60239/multi-point-evaluations-of-a-polynomial-mod-p
- http://cs.stackexchange.com/questions/60364/can-we-evaluate-a-polynomial-of-degree-n-modulo-m-at-all-m-points-faster-than-Θ
- http://cs.stackexchange.com/questions/60498/polynomial-evaluation-at-the-powers-of-primitive-root-of-a-prime-number (now deleted by its author)

I stress the point that discussing a problem on a live contest is forbidden.

How to prevent people do cheat?

In my opinion, the current rule statement is maybe not clear enough. Can this be improved?

For your information, you can solve this problem by mixed-radix FFT (consider the prime factorization of 786433-1).