最简题解来了！！！

#include<iostream>
#include<string>
using namespace std;
int main(){
string s1,s2,sub1;
cin>>s1>>s2;
s1=s1+s1;
s2=s2+s2;
int l=0;
for(int i=0;i<s1.size()-l;i++){
for(int j=l+1;j<s1.size()-i;j++){
sub1=s1.substr(i,j);
if(sub1.size()>l && s2.find(sub1)!=string::npos) l=sub1.size();
}
}
if(l>s1.size()/2) cout <<s1.size()/2;
else if(l>s2.size()/2) cout <<s2.size()/2;
else cout <<l;
}