ENG  RUS Timus Online Judge Online Judge
Problems
Authors
Online contests
Site news
Webboard
Problem set
Submit solution
Judge status
Guide
Register
Authors ranklist
Current contest
Scheduled contests
Past contests
Rules
back to board

## Discussion of Problem 1765. Error 404

I think this problem involves complex number operations
Posted by Shen Yang 22 Nov 2017 06:29
choose k numbers k1,k2...km such that sigma(cos((2*ki+1)*pi/n))==0&&sigma(sin((2*ki+1)*pi/n))==0

that is  sigma(cos((2*ki+1)*pi/n)+sin((2*ki+1)*pi/n)*i)==0
because cos(k*theta)+i*sin(k*theta)==(cos(theta)+i*sin(theta)^k

so it is sigma(cos(pi/n)+i*sin(pi/n))^(2*ki+1)==0

I think this problem must involved this...
Re: I think this problem involves complex number operations
Posted by Shen Yang 22 Nov 2017 08:14

is there O(polynomial)algo ? I only came up with a brute_force search idea..maybe it can pass..

brute_force search compnent part which is central symmetry

Edited by author 22.11.2017 08:15
Re: I think this problem involves complex number operations
Posted by Shen Yang 22 Nov 2017 13:05
seems can turn to minimum cut problem because there are only two prime factor,I didn't see it...