1.dfs全排列組數，an記得還原

2.如果范圍確定且只比較質數，isp比線性篩快，主要這個范圍太大了

https://www.luogu.com.cn/problem/P1218

#include<bits/stdc++.h>
using namespace std;
#define N 100011
typedef  long long ll;
typedef pair<ll,int> pii;
bool arr[100000011];
ll mod=0x3f3f3f3f3f3f;
vector<ll> prime;
int pos;
void xxs(ll x)
{prime.push_back(-1);for(int i=2;i<=x;i++){if(!arr[i]) prime.push_back(i),++pos;for(int j=1;j<=pos;j++){if(i*prime[j]>x) break;arr[i*prime[j]]=true;if(i%prime[j]==0) break;}}
}
int n;
ll powm(ll a,ll b)///快速冪 
{ll an=1;while(b){if(b%2) an=(an*a)%mod;b/=2;a=(a*a)%mod;}return an;
}
bool isp(int x)
{if(x==1||x==0) return false;///要考慮0和1 if(x==2) return true;for(int i=2;i*i<=x;i++){if(x%i==0) return false;}return true;
}
ll an;
int c=0;
void dfs(int x)
{if(x==n+1){if(isp(an/10)) if(!c){cout<<an/10,c++;///輸入格式比較嚴 }else cout<<'\n'<<an/10;return;}for(int i=1;i<=9;i++){an+=i;an*=10;if(isp(an/10)){dfs(x+1);}an/=10;///dfs記得還原 an-=i;}
}
int main()
{cin>>n;///xxs(powm(10,n)-1);///isp這里比xxs快 arr[0]=arr[1]=true;dfs(1);return 0;
}