/// <summary>
/// Displays the minimum tour information.
/// </summary>
/// <param name="points">The given points.</param>
/// <param name="tour">The indices of a minimum-length tour, in order, in the linklist.</param>
/// <param name="tourLen">The length of a shortest tour.</param>
private void DisplayResults(Point[] points, LinkedListCell <int> cell, double tourLen)
{
uxTourPoints.Items.Add(points[cell.Data]);
LinkedListCell <int> temp = cell;
while (temp.Next != null)
{
uxPanel.DrawLine(points[temp.Data], points[temp.Next.Data]);
uxTourPoints.Items.Add(points[temp.Next.Data]);
temp = temp.Next;
}
uxPanel.DrawLine(points[temp.Data], points[cell.Data]);
uxTourPoints.Items.Add(points[cell.Data]);
MessageBox.Show("Tour length: " + tourLen);
}
/// <summary>
/// Finds the minimum-length tour.
/// </summary>
/// <param name="curPoint">What point the function is currently at</param>
/// <param name="pathLentoCur">Current path length for the current path</param>
/// <param name="visited">Array to tell if the point has been visited before</param>
/// <param name="distances">2d Array that shows the distance between all points</param>
/// <param name="pointsInCurPath">Amount of points in the current path</param>
/// <param name="minTour">The minimum tour length as found by the algorithim</param>
/// <param name="bestTourFinish">Linkedlist cell linking to the optimal path</param>
/// <returns></returns>
private double ComputeMinumumLengthTour(int curPoint, double pathLentoCur, bool[] visited, double[,] distances, int pointsInCurPath, double minTour, out LinkedListCell <int> bestTourFinish)
{
bestTourFinish = null;
LinkedListCell <int> currentTour = new LinkedListCell <int>();
if (pointsInCurPath == visited.Length)
{
pathLentoCur += distances[0, curPoint];
LinkedListCell <int> tempcell = new LinkedListCell <int>();
tempcell.Data = curPoint;
bestTourFinish = tempcell;
return(pathLentoCur);
}
if (minTour < pathLentoCur)
{
bestTourFinish = null;
return(Double.PositiveInfinity);
}
else
{
for (int i = 0; i < visited.Length; i++)
{
if (visited[i] == false)
{
visited[i] = true;
LinkedListCell <int> outLinked;
double temp = ComputeMinumumLengthTour(i, pathLentoCur + distances[curPoint, i], visited, distances, pointsInCurPath + 1, minTour, out outLinked);
visited[i] = false;
if (temp < minTour)
{
minTour = temp;
currentTour = outLinked;
}
}
}
}
LinkedListCell <int> tempCell = new LinkedListCell <int>();
tempCell.Data = curPoint;
tempCell.Next = currentTour;
bestTourFinish = tempCell;
return(minTour);
}
/// <summary>
/// Displays the minimum tour information.
/// </summary>
/// <param name="points">Array of points entered by the user</param>
/// <param name="tour">Linked list of the optimal tour for the points</param>
/// <param name="tourLen">How long the optimal tour is</param>
private void DisplayResults(Point[] points, LinkedListCell <int> tour, double tourLen)
{
int first = tour.Data;
uxTourPoints.Items.Add(points[first]);
while (tour.Next != null)
{
uxPanel.DrawLine(points[tour.Data], points[tour.Next.Data]);
if (tour.Data != 0)
{
uxTourPoints.Items.Add(points[tour.Data]);
}
tour = tour.Next;
}
uxPanel.DrawLine(points[tour.Data], points[first]);
uxTourPoints.Items.Add(points[tour.Data]);
uxTourPoints.Items.Add(points[first]);
MessageBox.Show("Tour length: " + tourLen);
}
/// <summary>
/// Handles a Find Tour event.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void uxFindTour_Click(object sender, EventArgs e)
{
Point[] points = uxPanel.Points;
uxTourPoints.Items.Clear();
uxPanel.ClearLines();
if (points.Length < 2)
{
MessageBox.Show("You must plot at least 2 points.");
return;
}
double[,] distances = GetDistances(points);
int[] tour = new int[points.Length];
int n = points.Length;
bool[] visited = new bool[n];
visited[0] = true;
LinkedListCell <int> cell = new LinkedListCell <int>();
double minTour = OptimalLength(0, 0, visited, 1, distances, Double.PositiveInfinity, out cell);
DisplayResults(points, cell, minTour);
}
/// <summary>
/// Finds the minimum-length tour.
/// </summary>
/// <param name="curPoint">index of current point in current tour</param>
/// <param name="pathLenToCur">distance traveled from start to current point along the current path</param>
/// <param name="visited">marks which points have been visited in the current path visited</param>
/// <param name="pointsInCurPath">distances between all pairs of points</param>
/// <param name="distances">how many points are already in the current path</param>
/// <param name="minTour">shortest tour distance found so far</param>
/// <param name="bestTourFinish">stores the best tour in the LinkList</param>
/// <returns></returns>
private double OptimalLength(int curPoint, double pathLenToCur, bool[] visited, int pointsInCurPath, double[,] distances, double minTour, out LinkedListCell <int> bestTourFinish)
{
if (minTour <= pathLenToCur)
{
bestTourFinish = null;
return(pathLenToCur);
}
if (pointsInCurPath == visited.Length)
{
bestTourFinish = new LinkedListCell <int>();
bestTourFinish.Data = curPoint;
return(pathLenToCur + distances[curPoint, 0]);
}
LinkedListCell <int> temp = new LinkedListCell <int>();
for (int i = 0; i < visited.Length; i++)
{
if (visited[i] == false)
{
visited[i] = true;
double curr = OptimalLength(i, (pathLenToCur + distances[i, curPoint]), visited, pointsInCurPath + 1, distances, minTour, out bestTourFinish);
if (curr < minTour)
{
minTour = curr;
temp = bestTourFinish;
}
visited[i] = false;
}
}
LinkedListCell <int> cell = new LinkedListCell <int>();
cell.Data = curPoint;
cell.Next = temp;
bestTourFinish = cell;
return(minTour);
}
