int strStr(string haystack, string needle) {

     if (needle.empty())

         return ;

     int M = haystack.size();

     int N = needle.size();

     for (int i = ; i <= M - N; i++)

     {

         int j;

         for (j = ; j < N; j++)

         {

             if (needle[j] != haystack[i + j])

             {

                 break;

             }

         }

         if (j == N)

             return i;

     }

     return -;

 }

 int strStr(string haystack, string needle) {

     if (needle.empty())

         return ;

     int M = haystack.size();

     int N = needle.size();

     char* m = new char[M + ];

     char* n = new char[N + ];

     memcpy(m, haystack.c_str(), M);

     memcpy(n, needle.c_str(),    N);

     m[M] = '\0';

     n[N] = '\0';

     for (int i = ; i <= M - N; i++)

     {

         if ( == memcmp(&m[i], n, N))

         {

             delete[] m;

             delete[] n;

             return i;

         }

     }

     delete[] m;

     delete[] n;

     return -;

 }