题解 | BFS

#include <iostream>
using namespace std;

int main() {
    string s;
    cin >> s;

    if (s.size() < 3) {
        cout << -1 << endl;
    } else {
        for (int i = 0; i < s.size() - 2; i++) {
            if (s[i] == 'b' || s[i] == 'B') {
                if (s[i + 1] == 'o' || s[i + 1] == 'O') {
                    if (s[i + 2] == 'b' || s[i + 2] == 'B') {
                        cout << i << endl;
                        break;
                    }
                }
            }
            if (i == s.size() - 3) {
                cout << -1 << endl;
                break;
            }
        }
    }
}
// 64 位输出请用 printf("%lld")