docs: private void step4(DBIDRef id, WritableDBIDDataStore pi, WritableDoubleDataStore lambda, DBIDs processedIDs) {
      DBIDVar p_i = DBIDUtil.newVar();
      // for i = 1..n
      for(DBIDIter it = processedIDs.iter(); it.valid(); it.advance()) {
        double l_i = lambda.doubleValue(it);
        pi.assignVar(it, p_i); // p_i = pi(it)
        double lp_i = lambda.doubleValue(p_i);
  
        // if L(i) >= L(P(i))
        if(l_i >= lp_i) {
          // P(i) = n+1
          pi.put(it, id);
        }
      }
    }