alphabet

void alphabet_make(const char * codeword, char * a) {
  int was[27];
  for (int i=0;i<27;i++) was[i] = 0;
  while ((*codeword)>='a' && (*codeword)<='z') {
    if (!was[(*codeword)-'a']) {
      *a = (*codeword);
      a++;
    }
    was[(*codeword)-'a'] = 1;
    codeword++;
  }
  for (char i='a';i<='z';i++) {
    if (!was[i-'a']) {
      *a = i;
      a++;
    }
  }
}