![](https://img.laitimes.com/img/__Qf2AjLwojIjJCLyojI0JCLiAzNfRHLGZkRGZkRfJ3bs92YsYTMfVmepNHLxUEVPNTSU5kMRpHW4Z0MMBjVtJWd0ckW65UbM5WOHJWa5kHT20ESjBjUIF2X0hXZ0xCMx81dvRWYoNHLrdEZwZ1Rh5WNXp1bwNjW1ZUba9VZwlHdssmch1mclRXY39CXldWYtlWPzNXZj9mcw1ycz9WL49zZuBnL0ADN1UTOzYTMzEzNwEjMwIzLc52YucWbp5GZzNmLn9Gbi1yZtl2Lc9CX6MHc0RHaiojIsJye.png)
題目位址
#include<cstdio>
#include<iostream>
#include<string>
using namespace std;
int n,k;
bool check(long long int sum)
{
if(sum==1) return false;
if(sum==0) return false;
for(int i=2;i<=sum/i;i++)
if(sum%i==0) return false;
return true;
}
int main(void)
{
cin>>n>>k;
string s; cin>>s;
for(int i=0;i<=n-k;i++)
{
string temp=s.substr(i,k);
long long int sum=0;
for(int j=0;j<k;j++)
{
sum=sum*10+temp[j]-'0';
}
if(check(sum))
{
cout<<temp<<endl;
return 0;
}
}
cout<<"404"<<endl;
return 0;
}
#include<cstdio>
#include<iostream>
#include<string>
using namespace std;
int n,k,flag;
string s;
bool check(string s)
{
int sum=stoi(s);
if(sum==1) return false;
for(int i=2;i<=sum/i;i++) if(sum%i==0) return false;
return true;
}
int main(void)
{
cin>>n>>k;
cin>>s;
for(int i=0;i+k<=s.size();i++)
{
string temp=s.substr(i,k);
if(check(temp))
{
flag=1,cout<<temp<<endl;
break;
}
}
if(!flag) cout<<"404"<<endl;
}