code: private double spfR(InfoTree it1, InfoTree it2) {
  
  		int fReversedPostorder = it1.getSize() - 1 - it1.info[POST2_PRE][it1.getCurrentNode()];
  		int gReversedPostorder = it2.getSize() - 1 - it2.info[POST2_PRE][it2.getCurrentNode()];
  
  		int minRKR = it2.info[RPOST2_MIN_RKR][gReversedPostorder];
  		int[] rkr = it2.info[RKR];
  		if (minRKR > -1) for (int j = minRKR; rkr[j] < gReversedPostorder; j++) treeEditDistRev(it1, it2, fReversedPostorder, rkr[j]);
  		treeEditDistRev(it1, it2, fReversedPostorder, gReversedPostorder);
  
  		return it1.isSwitched() ? delta[it2.getCurrentNode()][it1
  				.getCurrentNode()]
  				+ deltaBit[it2.getCurrentNode()][it1.getCurrentNode()]
  				* costMatch : delta[it1.getCurrentNode()][it2.getCurrentNode()]
  				+ deltaBit[it1.getCurrentNode()][it2.getCurrentNode()]
  				* costMatch;
  	}
docs: Single-path function for right-most path based on symmetric version of
  Zhang and Shasha algorithm.
  
  @param it1
  @param it2
  @return distance between subtrees it1 and it2