[数学][广义欧拉定理]上帝与集合的正确用法

Posted 2021-01-11 lllxq

AC代码：

#include<cstdio>
#include<algorithm>
typedef long long ll;
using namespace std;

ll phi[10000005];
ll prime[10000005],num=0;
bool vis[10000005];

void get_phi(ll n=10000000){
  phi[1]=1;
  for(ll i=2;i<=n;i++){
    if(!vis[i]) prime[++num]=i,phi[i]=i-1;
    for(ll j=1;j<=num;j++){
        ll k=i*prime[j];
        if(k>n) break;
        vis[k]=1;
        if(i%prime[j]==0){
            phi[k]=phi[i]*prime[j];
            break;
        }
        phi[k]=phi[i]*(prime[j]-1);
    }
  }
  return ;
}

ll qpow(ll a,ll b,ll mod){
  ll ret=1;
  while(b){
    if(b&1) ret=ret*a%mod;
    a=a*a%mod;
    b>>=1;
  }
  return ret;
}

ll solve(ll p){
  if(p==1) return 0;
  return qpow(2,solve(phi[p])+phi[p],p);
}

int main()
{
    get_phi();
    ll t;scanf("%lld",&t);
    while(t--){
        ll p;scanf("%lld",&p);
        printf("%lld
",solve(p));
    }
    return 0;
}