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Copy pathGraph.cs
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79 lines (65 loc) · 2.12 KB
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using System.Collections.Generic;
namespace CodingProblems
{
public class Graph
{
private Dictionary<string, Dictionary<string, int>> Vertices { get; set; }
public void Add(string value, Dictionary<string, int> edges)
{
Vertices[value] = edges;
}
public Graph()
{
Vertices = new Dictionary<string, Dictionary<string, int>>();
}
public List<string> ShortestPath(string start, string finish)
{
var previous = new Dictionary<string, string>();
var distances = new Dictionary<string, int>();
var nodes = new List<string>();
List<string> path = null;
foreach (var vertex in Vertices)
{
if (vertex.Key == start)
{
distances[vertex.Key] = 0;
}
else
{
distances[vertex.Key] = int.MaxValue;
}
nodes.Add(vertex.Key);
}
while (nodes.Count != 0)
{
nodes.Sort((x, y) => distances[x] - distances[y]);
var smallest = nodes[0];
nodes.Remove(smallest);
if (smallest == finish)
{
path = new List<string>();
while (previous.ContainsKey(smallest))
{
path.Add(smallest);
smallest = previous[smallest];
}
break;
}
if (distances[smallest] == int.MaxValue)
{
break;
}
foreach (var neighbor in Vertices[smallest])
{
var alt = distances[smallest] + neighbor.Value;
if (alt < distances[neighbor.Key])
{
distances[neighbor.Key] = alt;
previous[neighbor.Key] = smallest;
}
}
}
return path;
}
}
}