Calculating the Critical Path

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The critical path calculation is the same as that performed in the previous chapter. However, both the N1NHood and the new neighborhood (see Creating the Relocate Neighborhood) require the critical path to be calculated in order to generate moves. With our previous implementation, we would unnecessarily calculate the critical path twice, once for each neighborhood. To avoid this we add a _needsRecomputing flag to the CriticalPath object. This flag can be set using a public method:

  void needsRecomputing() { _needsRecomputing = IloTrue; }

IloArray<IloResourceConstraint>& CriticalPath::computeCP(
                                       IloSchedulerSolution solution,
                                       IloInt& cpSize) {
  if (_needsRecomputing) {
    IloInt nbCriticalRCs = 0;
    RCSortElement *sortArray = getCriticalRCs(solution, nbCriticalRCs);
    
    // pick one (randomly selected) critical path
    pickRandomCP(sortArray, solution, nbCriticalRCs);
    delete [] sortArray;
    _needsRecomputing = IloFalse;
  }

  cpSize = _cpSize;
  return _cpArray;
}