// The main function that finds shortest distances from src
// to all other vertices using Bellman-Ford algorithm. The
// function also detects negative weight cycle
internal virtual void BellmanFord(GraphBellmanFord graph, int src)
{
int V = graph.V, E = graph.E;
int[] dist = new int[V];
// Step 1: Initialize distances from src to all other
// vertices as INFINITE
for (int i = 0; i < V; ++i)
{
dist[i] = int.MaxValue;
}
dist[src] = 0;
// Step 2: Relax all edges |V| - 1 times. A simple
// shortest path from src to any other vertex can
// have at-most |V| - 1 edges
for (int i = 1; i < V; ++i)
{
for (int j = 0; j < E; ++j)
{
int u = graph.edge[j].src;
int v = graph.edge[j].dest;
int weight = graph.edge[j].weight;
if (dist[u] != int.MaxValue && dist[u] + weight < dist[v])
{
dist[v] = dist[u] + weight;
}
}
}
// Step 3: check for negative-weight cycles. The above
// step guarantees shortest distances if graph doesn't
// contain negative weight cycle. If we get a shorter
// path, then there is a cycle.
for (int j = 0; j < E; ++j)
{
int u = graph.edge[j].src;
int v = graph.edge[j].dest;
int weight = graph.edge[j].weight;
if (dist[u] != int.MaxValue && dist[u] + weight < dist[v])
{
Console.WriteLine("Graph contains negative weight cycle");
}
}
printArr(dist, V);
}
internal Edge(GraphBellmanFord outerInstance)
{
this.outerInstance = outerInstance;
src = dest = weight = 0;
}
