public BellmanFord(WeightedGraph graph, int s)
{
this.G = graph;
G.ValidateVertex(s);
this.s = s;
dis = new int[G.V];
Pre = new int[G.V];
for (int i = 0; i < dis.Length; i++)
{
dis[i] = int.MaxValue;
Pre[i] = -1;
}
dis[0] = 0;
Pre[s] = 0;
//进行V-1次松弛操作
for (int j = 1; j < G.V; j++)
{
for (int i = 0; i < G.V; i++)
{
foreach (var item in G.GetAdj(i))
{
if (dis[i] != int.MaxValue)
{
int temp = dis[i] + G.GetWeight(i, item);
if (temp < dis[item])
{
dis[item] = temp;
Pre[item] = i;
}
}
}
}
}
//再进行一次松弛操作,判断是否有负权边
for (int i = 0; i < G.V; i++)
{
foreach (var item in G.GetAdj(i))
{
if (dis[i] != int.MaxValue)
{
int temp = dis[i] + G.GetWeight(i, item);
if (temp < dis[item])
{
hasNegCycle = true;
break;
}
}
}
}
}
public Dijkstra(WeightedGraph graph, int s)
{
this.G = graph;
G.ValidateVertex(s);
this.s = s;
dis = new int[G.V];
Pre = new int[G.V];
for (int i = 0; i < dis.Length; i++)
{
dis[i] = int.MaxValue;
Pre[i] = -1;
}
dis[0] = 0;
Pre[s] = 0;
visited = new bool[G.V];
while (true)
{
int curDis = int.MaxValue, cur = -1;
//1.遍历dis数组,找到未被定下的最小的节点
for (int i = 0; i < G.V; i++)
{
if (!visited[i] && dis[i] < curDis)
{
cur = i;
curDis = dis[i];
}
}
if (cur == -1)
{
break;
}
//2.确定过这个最小节点的最短路径
visited[cur] = true;
//3.根据这个节点的最短路的大小,更新其他节点路径的长度
foreach (var item in G.GetAdj(cur))
{
if (!visited[item])
{
int temp = dis[cur] + G.GetWeight(cur, item);
if (temp < dis[item])
{
dis[item] = temp;
Pre[item] = cur;
}
}
}
}
}
public bool isConnected(int v)
{
G.ValidateVertex(v);
return(dis[v] != int.MaxValue);
}
//public IEnumerable<int> Path(int t)
//{
// List<int> re = new List<int>();
// if (!isConnected(t))
// {
// return re;
// }
// int cur = t;
// while (Pre[cur] != cur)
// {
// re.Add(cur);
// cur = Pre[cur];
// }
// re.Add(s);
// re.Reverse();
// return re;
//}
public bool isConnected(int v, int w)
{
G.ValidateVertex(v);
G.ValidateVertex(w);
return(dis[v, w] != int.MaxValue);
}
public bool isConnected(int v)
{
G.ValidateVertex(v);
return(visited[v]);
}
