/// <summary> /// performs a Branch and Bound search of the state space of partial tours /// stops when time limit expires and uses BSSF as solution /// </summary> /// <returns>results array for GUI that contains three ints: cost of solution, time spent to find solution, number of solutions found during search (not counting initial BSSF estimate)</returns> public string[] bBSolveProblem() { string[] results = new string[3]; results[COST] = "not implemented"; // load results into array here, replacing these dummy values results[TIME] = "-1"; results[COUNT] = "-1"; int count = 0; Console.Out.WriteLine("City costs: "); for (int j = 0; j < Cities.Length; j++) { for (int h = 0; h < Cities.Length; h++) { Console.Write(Cities[j].costToGetTo(Cities[h]) + ","); } Console.WriteLine(); } Stopwatch timer = new Stopwatch(); timer.Start(); PriorityQueue queue = new PriorityQueue(); queue.make_queue(Cities.Length * Cities.Length * Cities.Length * Cities.Length); //Here I run the greedy algorithm and use that BSSF result as my starting BSSF greedySolveProblem(); Console.Out.WriteLine("Greedy BSSF: " + costOfBssf()); matrix_and_bound initial_matrix = construct_initial_matrix(); for (int j = 0; j < Cities.Length; j++) { for (int h = 0; h < Cities.Length; h++) { Console.Write(initial_matrix.Matrix[j, h] + ","); } Console.WriteLine(); } Console.WriteLine(initial_matrix.Lower_bound); //Console.WriteLine(); //This loop will do my initial population of the queue by looping through each city and getting the lower bound for (int i = 0; i < Cities.Length; i++) { for (int k = 0; k < Cities.Length; k++) { if (i != k) { //I need to get the lower bound of each reduced matrix and the bound matrix_and_bound current = matrix_reduction(initial_matrix, i, k); //Console.WriteLine(); //If the lower bound is less than current bssf add to queue for later checking, otherwise ignore if (current.Lower_bound < costOfBssf()) { //need to create new state_data object with state data set state_data data = new state_data(); //I guess depth doesn't matter to be exact so long as it's relative, so I'll keep this first one as 0 data.Depth = 0; data.Mb = current; data.add_city(Cities[i]); data.add_city(Cities[k]); data.add_city_index(i); data.add_city_index(k); data.set_priority(); Console.Out.WriteLine("bound " + data.Mb.Lower_bound); //I'm not sure this id is necessary but I'll have to see data.Id = id; queue.insert(data, id); id++; } } } } Console.Out.WriteLine("Queue length Initial " + queue.Length); //now run while queue is not empty and timer is less than 60 while (timer.Elapsed.TotalSeconds < 60 && queue.Length > 0) { //pop off of queue and repeat above matrix reduction process state_data current = queue.delete_min(); //if it's greater or equal to the current bssf I can just ignore it, this is the culling if (current.Mb.Lower_bound < costOfBssf()) { //Priority queue looks like it's working //Console.Out.WriteLine(current.Mb.Lower_bound); /* * Now I need to matrix reduce each child of the current node, * see if it's still smaller than the current bssf if it's a leaf node * I put it as the current bssf, otherwise I push it on the queue */ for (int k = 0; k < Cities.Length; k++) { if (!current.City_list.Contains(k)) { matrix_and_bound child = matrix_reduction(current.Mb, (int)current.City_list[current.City_list.Count - 1], k); //Console.Out.WriteLine("here"); //Console.Out.WriteLine("Current depth: " + ); for (int j = 0; j < Cities.Length; j++) { for (int h = 0; h < Cities.Length; h++) { Console.Write(child.Matrix[j, h] + ","); } Console.WriteLine(); } Console.WriteLine(child.Lower_bound); if (child.Lower_bound < costOfBssf()) { //need to create new state_data object with state data set state_data data = new state_data(); //I guess depth doesn't matter to be exact so long as it's relative, so I'll keep this first one as 0 data.Depth = current.Depth + 1; data.Mb = child; //The last value in the path is the current city data.Path = current.Path; data.City_list = current.City_list; data.add_city(Cities[k]); /* Console.Out.WriteLine("The Current Path and length " + data.City_list.Count); * for (int j = 0; j < data.City_list.Count; j++) * { * Console.Out.Write(data.City_list[j] + "->"); * } * Console.Out.WriteLine();*/ data.City_list = current.City_list; data.add_city_index(k); data.set_priority(); //Console.Out.WriteLine("Set Priority " + data.Priority); //I'm not sure this id is necessary but I'll have to see data.Id = id; id++; // Console.Out.WriteLine("Intermediate Lower Bound " + data.Mb.Lower_bound); if (data.City_list.Count < Cities.Length) { queue.insert(data, id); } else if (data.Mb.Lower_bound < costOfBssf())//it's a leaf node and it's less than the current BSSF { Console.Out.WriteLine("Current Lower Bound " + costOfBssf()); Console.Out.WriteLine("Final Lower Bound " + data.Mb.Lower_bound); for (int j = 0; j < data.City_list.Count; j++) { Console.Out.Write(data.City_list[j] + "->"); } bssf = new TSPSolution(data.Path); count++; } } } } } } results[COST] = costOfBssf().ToString(); results[TIME] = timer.Elapsed.ToString(); results[COUNT] = count.ToString(); return(results); }