Developing Programming Tools to Handle Traveling Salesman Problem by the Three Object-Oriented Languages

Algorithm 7

Abstract pseudocodes for LK.

1      List<Node> ActiveNodes;// to implement “don’t-look bits”

2      void LK(Tour tour)

3      {

4       for each node X

5         Add X to ActiveNodes List;

6       while(active node is existed)

7       {

8         Node N = remove and return first node in ActiveNodes;

9         if(inner-LK(tour, X) <= 0)

10      inactive X;

11    }

12   }

1      int inner-LK(Tour tour, Node x)

2      {

3       Y    neighbor of X;

4       int partial-gain = |XY|;

5       break XY from tour;

6       Add Y to ActiveNodes List;

7       for each Z    candidate set of X

8       {

9         add YZ to tour;

10      Add Z to ActiveNodes List;

11      partial-gain = partial-gain + |YZ|;

12      if tour is feasible (tour closing up by one edge is possible)

13      {

14        if (partial-gain  −  last added edge cost > 0 then)

15        {

16          close up tour;

17          return  partial-gain  −  last added edge cost;

18        }

19        else

20        {

21          int g = inner-LK(tour, x);

22          if (g < 0)

23          {

24             break YZ; //test another.

25          }

26          else

27          {

28            return g;

29          }

30        }

31      }

32    }

33    add XY to tour; //breaking XY was unsuccessful.

(34)    remove Y from ActiveNodes List;

(35)    return 0;

(36)   }