/// <summary>
/// Method for running path calculation for each pair in input file
/// </summary>
/// <param name="map">Map of graph</param>
/// <param name="question">List of pairs of nodes to find distance between</param>
private static void FindAllPaths(ref int[,] map, List <string[]> question)
{
GraphPath path;
foreach (string[] startEnd in question)
{
path = new GraphPath();
FindPath(startEnd);
}
}
/// <summary>
/// Main part of Dijkstra's algorythm
/// </summary>
/// <param name="startEnd">Star and end nodes</param>
private static void FindPath(string[] startEnd)
{
char startNode = startEnd[0][0];
char endNode = startEnd[1][0];
int row;
int size = map.GetLength(0);
PriorityQueue queue = new PriorityQueue();
queue.Enqueue(new Tuple <char, int, char>(startNode, 0, startNode));
Dictionary <char, int[]> visited = new Dictionary <char, int[]>();
while (queue.Count > 0)
{
Tuple <char, int, char> currentNode = queue.Dequeue();
char previousNode = currentNode.Item3;
row = currentNode.Item1 - 65;
int currentDistance = currentNode.Item2;
if (!visited.ContainsKey(currentNode.Item1))
{
visited.Add(currentNode.Item1, new int[] { currentDistance, previousNode });
}
else if (visited.ContainsKey(currentNode.Item1) && visited[currentNode.Item1][0] > currentNode.Item2)
{
visited[currentNode.Item1][0] = currentNode.Item2;
visited[currentNode.Item1][1] = previousNode;
}
for (int i = 0; i < size; i++)
{
if (map[row, i] != 0 && !visited.ContainsKey((char)(i + 65)))
{
queue.Enqueue(new Tuple <char, int, char>((char)(i + 65), map[row, i] + currentDistance, currentNode.Item1));
}
}
}
if (visited.ContainsKey(endNode))
{
GraphPath result = RebuildPath(visited, startEnd);
Console.WriteLine(result);
}
else
{
Console.WriteLine($"No path found between {startNode} and {endNode}!");
}
}
/// <summary>
/// Method for finding out final path based on list of distances from begining
/// </summary>
/// <param name="visited">List of nodes accessible from start node and distances from it with previous nodes for each other</param>
/// <param name="startEnd">Path start and end</param>
/// <returns></returns>
private static GraphPath RebuildPath(Dictionary <char, int[]> visited, string[] startEnd)
{
char startNode = startEnd[0][0];
char endNode = startEnd[1][0];
char currentNode = endNode;
GraphPath result = new GraphPath();
result.Length = visited[endNode][0];
result.Nodes.Add(currentNode.ToString());
while (currentNode != startNode)
{
currentNode = (char)visited[currentNode][1];
result.Nodes.Add(currentNode.ToString());
}
return(result);
}
