题解 | BFS

import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.nextLine(), str = "bob";
        s = s.toLowerCase();
        int res = -1;
        for (int i = 0; i <= s.length() - 3; i++) {
            int k = 0;
            for (int j = 0; j < str.length(); j++) {
                if (s.charAt(i + j) == str.charAt(j)) {
                    k++;
                    //System.out.println(s.charAt(i + j));
                }else break;
            }
            if (k == 3) {
                res = i;
                break;
            }
            //System.out.println(k);
        }
        if (res != -1)System.out.println(res);
        else System.out.println(res);
    }
}