题解 | BFS

#include<bits/stdc++.h>
using namespace std;
int main()
{
string s;
cin>>s;
string lower_s=s;
for(int i=0;i<lower_s.length();i++)
{
	lower_s[i]=tolower(lower_s[i]);
}
string target="bob";
size_t pos=lower_s.find(target);
if(pos!=string::npos)
{
	cout<<pos;
}
else
{
	cout<<-1;
}
return 0;
}