code: private void step1(DBIDRef id, WritableDBIDDataStore pi, WritableDoubleDataStore lambda) {
      // P(n+1) = n+1:
      pi.put(id, id);
      // L(n+1) = infinity
      // Initialized already.
      // lambda.putDouble(id, Double.POSITIVE_INFINITY);
    }
docs: First step: Initialize P(id) = id, L(id) = infinity.
  
  @param id the id of the object to be inserted into the pointer
  representation
  @param pi Pi data store
  @param lambda Lambda data store