int sunday(string str, string pattern) {

    int str_len = str.length();

    int pat_len = pattern.length();

    int char_pos[];

    for (int i = ; i<; i++) char_pos[i] = -;

    for (int i = pat_len - ; i>=; i--) char_pos[pattern[i]] = i;

    int i = ;

    int j = ;

    while (i + pat_len <= str_len) {

        while (j < pat_len && str[i] == pattern[j]) {

            i++, j++;

        }

        if (j == pat_len) return i - pat_len;

        int k = i + pat_len - j;

        int p = ;

        while ( k < str_len && (p = char_pos[str[k]]) == -) {

            k += pat_len;

        }

        i = k - p;

        j = ;

    }

    return -;

}

 int sunday(const char* pattern, const char* str) {

     if (pattern == NULL || str == NULL) {

         return -;

     }

     int slen = , plen = ;

     while (pattern[plen] != '\0') plen++;

     while (str[slen] != '\0') slen++;

     int tbl[];

     for (int i=; i<; i++) tbl[i] = -;

     for (int i=; i<plen; i++) tbl[pattern[i]] = i;

     int pi = , si = ;

     while (si < slen) {

         while (str[si] == pattern[pi] && si < slen) si++, pi++;

         if (pi == plen) return si - plen;

         int nidx = plen - pi + si;

         int offset = tbl[str[nidx]];

         si = nidx - offset;

         pi = ;

     }

     return -;

 }