code: public double getValue(Configuration configuration) {
          double cost = this.problem.pathLength(configuration);
          if (this.problem.isSolution(configuration))
              return -cost;
          return Double.NEGATIVE_INFINITY;
  
          // if (this.problem.isSolution(configuration))
          //     return this.maxDistance - cost;
          // return -cost;
      }
docs: Default fitness for FastTSP algorithm.
  <p/>
  Returns positive number if configuration {@link TSP#isSolution(cz.cvut.felk.cig.jcop.problem.Configuration) is
  solution}, number equals -tourDistance.
  <p/>
  If configuration is not solution, returns negative infinity.
  
  @param configuration attributes to compute fitness
  @return fitness of attributes