子串寻找（find函数）

#include<bits/stdc++.h>
using namespace std;
int main(){
    string a,b;
    cin>>a>>b;
    if(a.find(b)!=-1) cout<<b<<" is substring of "<<a;
    else if(b.find(a)!=-1) cout<<a<<" is substring of "<<b;
    else cout<<"No substring";
    return 0;
}