first for bound=1e5,using matirx power to compute x0,x1  x[bound],x[bound+1] ,x[2*bound],x[2*bound+1].....  upper bound is 2*p   using map to record  (x[i*bound],x[i*bound+1])

I use this formula and discrete log algo to find candidate of xn+1

then continue to compute xn-1 xn-2 .... until we find (xi,xi+1) in the map then it is valid
otherwise it is invalid
complex : sqrt(p*log(p))

Edited by author 02.12.2017 15:17