[SDOI2011]计算器

Posted 2021-02-07 skip1978

bsgs

 

#include<cstdio>
#include<algorithm>
#include<iostream>
#include<cmath>
#include<map>
typedef long long ll;
inline int pow(int a,int b,const int mod){
    int ans=1;
    for(;b;b>>=1,a=ll(a)*a%mod)
        if(b&1)ans=ll(ans)*a%mod;
    return ans;
}
inline int phi(int mod){
    int ret=mod;
    for(int i=2;i*i<=mod;++i)
        if(mod%i==0){
            ret=ret/i*(i-1);
            while(mod%i==0)mod/=i;
        }
    if(mod!=1)ret=ret/mod*(mod-1);
    return ret;
}
inline int inv(int x,const int mod){return pow(x,mod-2,mod);}
std::map<int,int> map;
inline int solve(int y,int z,const int mod){
    map.clear();
    int q = sqrtl(mod), q2=q+10;
    for(int i=0,lm=1;i<=q;++i)
        map[lm]=i,lm=ll(lm)*y%mod;
    const int p = inv(pow(y,q,mod),mod);
    int ans=0;
    while(!map.count(z) && --q2)
        z = ll(z)*p%mod,ans+=q;
    if(map.count(z)) return ans + map[z];
    else return -1;
}
int main(){
    int t,k;
    std::cin >> t >> k;
    while(t--){
        int y,p,z;
        std::cin >> y >> z >> p;
        if(k == 1)
            std::cout << pow(y,z,p) << ‘
‘;
        if(k == 2){
            y%=p,z%=p;
            if(y==0&&z!=0){
                std::cout << "Orz, I cannot find x!
";
                continue;
            }
            std::cout << ll(z)*inv(y,p)%p << ‘
‘;;
        }
        if(k == 3){
            const int mod = p;
            y %= p,z%=p;
            if(y == 0 && z == 0){
                std::cout << "1
";
                continue;
            }
            if(y == 0 && z){
                std::cout << "Orz, I cannot find x!
";
                continue;
            }
            int res = solve(y,z,mod);
            if(res == -1){
                std::cout << "Orz, I cannot find x!
";
                continue;
            }
            std::cout << res << ‘
‘;
        }
    }
}