题解 | BFS

#include <iostream>
using namespace std;

int main() {
    string x, y = "bob";
    int d = 0, i;
    cin >> x;
    for (i = 0; x[i] != '\0'; i++) {
        if ((x[i] - 'A' == y[d] - 'a') || (x[i] == y[d])) d++;
        else if (((x[i] - 'A' == y[d] - 'a') || (x[i] == y[d]) || (x[i] - 'A' == y[d - 1] - 'a') || (x[i] == y[d - 1])) && i != 0&&x[i]!='o') continue;
        else d = 0;
        if (d == 3) break;
    }if (d == 3) cout << i - 2 << endl;
    else cout << -1 << endl;
    return 0;
}