11  #include <iostream>22  #include <string>33  #include <vector>4455  using namespace std;6677  int f(const string &s, const string &t)88  {99      int n = s.length(), m = t.length();10101111     vector<int> shift(128, m + 1);12121313     int i, j;14141515     for (j = 0; j < m; j++)1616         shift[t[j]] = m - j;17171818     for (i =0; i<= n - m; i += shift[s[i + m]]){1919         j =0;2020         while(j < m && s[i +j] == t[j]) j++;2121         if (j == m) return i;2222     }23232424     return -1;2525 }26262727 int main()2828 {2929     string a ,b;3030     cin >> a >> b;3131     cout << f(a, b) << endl;3232     return 0;3333 }

假设输入字符串由 ASCII 可见字符组成，完成下面的判断题和单选题：

判断题