code: public boolean checkMinDistIsZero(char[] a, char[] b) {
      for (int i = 0; i < a.length; i++) {
        if (charDistance(a[i], b[i]) > 1) {
          return false;
        }
      }
      return true;
    }
docs: Check for trivial mindist case.
  
  @param a first string.
  @param b second string.
  @return true if mindist between strings is zero.