code: private int calculateMinimizationProcessingStartIndex(String prevStr, String currStr)
      {
          int mpsIndex;
  
          if (!currStr.startsWith(prevStr))
          {
              //Loop through the corresponding indices of both Strings in search of the first index containing differing characters.
              //The _transition path of the substring of prevStr from this point will need to be submitted for minimization processing.
              //The substring before this point, however, does not, since currStr will simply be extending the right languages of the 
              //nodes on its _transition path.
              int shortestStringLength = Math.min(prevStr.length(), currStr.length());
              for (mpsIndex = 0; mpsIndex < shortestStringLength && prevStr.charAt(mpsIndex) == currStr.charAt(mpsIndex); mpsIndex++)
              {
              }
              ;
              /////
          }
          else
              mpsIndex = -1;    //If the prevStr is a prefix of currStr, then currStr simply extends the right language of the _transition path of prevStr.
  
          return mpsIndex;
      }
docs: 计算最小化的执行位置，其实是prevStr和currStr的第一个分叉点<br>
  Determines the start index of the substring in the String most recently added to the MDAG
  that corresponds to the _transition path that will be next up for minimization processing.
  <p/>
  The "minimization processing start index" is defined as the index in {@code prevStr} which starts the substring
  corresponding to the _transition path that doesn't have its right language extended by {@code currStr}. The _transition path of
  the substring before this point is not considered for minimization in order to limit the amount of times the
  equivalence classes of its nodes will need to be reassigned during the processing of Strings which share prefixes.
  
  @param prevStr the String most recently added to the MDAG
  @param currStr the String next to be added to the MDAG
  @return an int of the index in {@code prevStr} that starts the substring corresponding
  to the _transition path next up for minimization processing