poj 2417

 Accepted    8508K    391MS    C++   2004B
 相比下边，，优化太多太多了。。。
 /**
 baby-step-giant-step  因为数据量太大，，自己写hash

 **/
 #include <iostream>
 #include <cstdio>
 #include <cmath>
 #include <cstring>
 using namespace std;
 long long n,a,b;
 const int maxn = ;
 bool Hash[maxn];
 long long idx[maxn];
 long long val[maxn];

 void ex_gcd(long long a,long long b,long long &x,long long &y){
     if(b==){
         x=;
         y=;
         return ;
     }
     ex_gcd(b,a%b,x,y);
     long long tmp = x-(a/b)*y;
     x = y;
     y = tmp;
 }

 long long euler(long long n){
     long long i,tmp = n;
     for(i=;i*i<=n;i++)if(n%i==){
         tmp = tmp/i*(i-);
         while(n%i==)
             n = n/i;
     }
     if(n>)
         tmp = tmp/n*(n-);
     return tmp;
 }

 void Insert(long long id,long long num){
     long long k = num%maxn;
     while(Hash[k]&&val[k]!=num){
         k++;
         if(k==maxn) k = k-maxn;
     }
     if(!Hash[k]){
         Hash[k] =;
         idx[k] = id;
         val[k] = num;
     }
 }

 long long found(long long num){
     long long k = num%maxn;
     while(Hash[k]&&val[k]!=num){
         k++;
         if(k==maxn) k = k-maxn;
     }
     if(!Hash[k]){
         return -;
     }
     return idx[k];
 }

 long long baby_step(long long a,long long b,long long n){
     long long m = ceil(sqrt(euler(n)+0.5));
     memset(Hash,false,sizeof(Hash));
     memset(idx,-,sizeof(idx));
     memset(val,-,sizeof(val));
     long long d=;
     for(long long i=;i<m;i++){
         Insert(i,d);
         d = d*a%n;
     }
     long long res =;
     long long x,y;
     for(long long i=;i<m;i++){
         ex_gcd(res,n,x,y);
         long long tmp = x*b%n;
         tmp = (tmp%n+n)%n;
         long long k = found(tmp);
         if(k!=-){
             return (i)*m+k;
         }
         res = res*d%n;
     }
     return -;
 }

 int main()
 {
     while(scanf("%I64d%I64d%I64d",&n,&a,&b)==){
         long long res = baby_step(a,b,n);
         if(res==-)
             printf("no solution\n");
         else
             printf("%I64d\n",res);
     }
     return ;
 }

 -----------------------------------分割线---------------------------------------
 /**
106 高次方程。。。baby-step-giant-step 算法
 Accepted   4592K4     516MS      C++1104B
 **/
 #include <iostream>
 #include <cstdio>
 #include <math.h>
 #include <map>
 using namespace std;

 long long powmod(long long a,long long b,long long n){
     if(b==)
         return ;
     long long c =;
     while(b){
         if(b&)
             c =c*a%n;
         a =a*a%n;
         b>>=;
     }
     return c;
 }

 long long logmod(long long a,long long b,long long n){
     long long m,v,e=,i;
     m = ceil(sqrt(n+0.5));
     //cout<<(double)(n-1)*1.0/m<<endl;
     //long long m_n = powmod(a,m,n);
     v = powmod(a,n--m,n);
     map<long long ,long long >x;
     x.clear();
     x[] =m;
     for(i=;i<m;i++){
         e = e*a%n;
         if(!x[e]) x[e]=i;
     }
     for(i=;i<m;i++){
         if(x[b]){
             long long num = x[b];
             x.clear();
             return i*m+(m==num?:num);
         }
         b = b*v%n;
     }
     return -;
 }

 int main()
 {
     long long a,b,n;
     while(scanf("%I64d%I64d%I64d",&n,&a,&b)==){
         long long res = logmod(a,b,n);
         if(res==-)
             printf("no solution\n");
         else
             printf("%I64d\n",res);
     }
     return ;
 }