http://www.lydsy.com/JudgeOnline/problem.php?id=2242
#include<map> #include<cmath> #include<cstdio> using namespace std; int y,z,p; map<int,int>mp; int Pow(int a,int b,int m) { int ans=1; for(;b;a=1LL*a*a%m,b>>=1) if(b&1) ans=1LL*ans*a%m; return ans; } int gcd(int a,int b) { return !b ? a : gcd(b,a%b); } void exgcd(int a,int b,long long &x,long long &y) { if(!b) { x=1; y=0; return; } exgcd(b,a%b,y,x); y-=a/b*x; } void bsgs() { mp.clear(); int m=ceil(sqrt(p)); int mul=z; //mp[z]=0; for(int j=1;j<=m;++j) { mul=1LL*y*mul%p; mp[mul]=j; } int am=Pow(y,m,p); mul=1; for(int j=1;j<=m;++j) { mul=1LL*mul*am%p; if(mp.find(mul)!=mp.end()) { printf("%d\n",j*m-mp[mul]); return; } } puts("Orz, I cannot find x!"); } int main() { int T,k; scanf("%d%d",&T,&k); if(k==1) while(T--) { scanf("%d%d%d",&y,&z,&p); printf("%d\n",Pow(y,z,p)); } else if(k==2) { long long x0,y0; int g; while(T--) { scanf("%d%d%d",&y,&z,&p); g=gcd(y,p); if(z%g) puts("Orz, I cannot find x!"); else { y/=g; p/=g; exgcd(y,p,x0,y0); x0=(x0%p+p)%p; x0=x0*z/g%p; printf("%lld\n",x0); } } } else while(T--) { scanf("%d%d%d",&y,&z,&p); if(!(y%p)) puts("Orz, I cannot find x!"); else bsgs(); } return 0; }