/// <summary>
/// Function to build graph of edges between the zipcodes.
/// </summary>
/// <param name="zipCode1"></param>
/// <param name="zipCode2"></param>
/// <param name="distance">distance between zipcode1 and zipcode2</param>
private void BuildGraphEdges(string zipCode1, string zipCode2, int distance)
{
ZipNodes zipNode1 = new ZipNodes(zipCode2, distance);
ZipNodes zipNode2 = new ZipNodes(zipCode1, distance);
if (!graph[zipCode1].Contains(zipNode1))
{
graph[zipCode1].Add(zipNode1);
}
if (!graph[zipCode2].Contains(zipNode2))
{
graph[zipCode2].Add(zipNode2);
}
}
/// <summary>
/// Function that fetches the shortest path between the source and destination
/// </summary>
/// <param name="source"></param>
/// <param name="destination"></param>
private int ShortestPath(string source, string destination)
{
int shortestDistance = int.MaxValue;
vertices = graph.Count;
ZipNodes zipCodeObj;
//To store finalised distances
Dictionary <string, int> distance = new Dictionary <string, int>();
//Sorted dictionary used in the form of a min heap
SortedSet <ZipNodes> sortedSet = new SortedSet <ZipNodes>(new CustomComparer());
Dictionary <string, ZipNodes> trackingHashMap = new Dictionary <string, ZipNodes>();
zipCodeObj = new ZipNodes(source, 0);
trackingHashMap.Add(source, zipCodeObj);
sortedSet.Add(zipCodeObj);
while (distance.Count <= vertices)
{
string currentZip = sortedSet.ElementAt(0).zipCode;
int currentDistance = sortedSet.ElementAt(0).distance;
distance.Add(currentZip, currentDistance);
if (currentZip == destination)
{
if (result.ContainsKey(source) && result[source] > distance[destination])
{
//result[source] = distance[destination];
return(distance[destination]);
}
}
sortedSet.Remove(trackingHashMap[currentZip]);
for (int i = 0; i < graph[currentZip].Count; i++)
{
if (!distance.ContainsKey(graph[currentZip][i].zipCode))
{
if (!trackingHashMap.ContainsKey(graph[currentZip][i].zipCode))
{
ZipNodes newZipCodeObj = new ZipNodes(graph[currentZip][i].zipCode, graph[currentZip][i].distance + currentDistance);
sortedSet.Add(newZipCodeObj);
trackingHashMap.Add(graph[currentZip][i].zipCode, newZipCodeObj);
}
else
{
if (trackingHashMap[graph[currentZip][i].zipCode].distance > graph[currentZip][i].distance + currentDistance)
{
sortedSet.Remove(trackingHashMap[graph[currentZip][i].zipCode]);
trackingHashMap[graph[currentZip][i].zipCode].distance = graph[currentZip][i].distance + currentDistance;
sortedSet.Add(trackingHashMap[graph[currentZip][i].zipCode]);
}
}
}
}
}
return(shortestDistance);
}
