BSGS算法，预处理出ϕ(c)−−−−√内的a的幂，每次再一块一块的往上找，转移时将b乘上逆元，哈希表里O(1)查询即可

#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

#include<cmath>

#include<map>

#define LL long long

long long a,b,c,m;

bool bo=0;

std::map<long long,int> pp;

std::map<long long,bool> vis;

LL exgcd(LL o,LL p,LL &x,LL &y){

    if(p==0){

        x=1;y=0;

        return o;

    }

    LL gcd=exgcd(p,o%p,x,y);

    LL t=x;

    x=y;

    y=t-(o/p)*x;

    return gcd;

}

int main(){

    while(scanf("%lld%lld%lld",&c,&a,&b)==3){

        pp.clear(); vis.clear(); bo=0;

        if(a%c==0){printf("no solution\n");continue;}

        m=(LL)ceil(sqrt((double)c));

        LL now=1;

        pp[now]=0; vis[now]=1;

        for(int i=1;i<m;i++){

            now=(now*a)%c;

            if(!vis[now]){vis[now]=1;pp[now]=i;}

        }

        now=(now*a)%c;

        LL x,y;

        LL d=exgcd(now,c,x,y);

        x=(x%c+c)%c;

        for(int i=0;i<=m;i++){

            if(vis[b]){

                printf("%lld\n",i*m+pp[b]);

                bo=1; break;

            }

            b=(b*x)%c;

        }

        if(bo==1)continue;

        printf("no solution\n");

    }

    return 0;

}