static int levenWithSwapsIC(S s, S t) {

  // degenerate cases

  if (s.equals(t)) return 0;

  int ls = s.length(), lt = t.length();

  if (ls == 0) return lt;

  if (lt == 0) return ls;

  int[] vx = new int[lt + 1];

  int[] v0 = new int[lt + 1];

  int[] v1 = new int[lt + 1];

  for (int i = 0; i < v0.length; i++) v0[i] = i;

  for (int i = 0; i < ls; i++) {

      v1[0] = i + 1;

      for (int j = 0; j < lt; j++) {

          int cost = equalsIgnoreCase(s.charAt(i), t.charAt(j)) ? 0 : 1;

          int d = min3(

            v1[j] + 1,     // delete

            v0[j + 1] + 1, // insert

            v0[j] + cost); // edit

          if (i > 0 && j > 0 && equalsIgnoreCase(s.charAt(i), t.charAt(j-1)) && equalsIgnoreCase(s.charAt(i-1), t.charAt(j)))

            d = min(d, vx[j-1] + 1); // transposition

          v1[j + 1] = d;

      }

      // rotate arrays

      int[] v = vx;

      vx = v0;

      v0 = v1;

      v1 = v;

  }

  return v0[lt];

}