public Folyed(WeightedGraph graph)
{
this.G = graph;
dis = new int[G.V, G.V];
Pre = new int[G.V];
for (int i = 0; i < dis.GetLength(0); i++)
{
for (int j = 0; j < dis.GetLength(1); j++)
{
dis[i, j] = int.MaxValue;
}
dis[i, i] = 0;
foreach (var j in G.GetAdj(i))
{
dis[i, j] = G.GetWeight(i, j);
}
}
//进行V-1次松弛操作
for (int j = 1; j < G.V; j++)
{
//以k为原点
for (int k = 0; k < G.V; k++)
{
dis[k, k] = 0;
//k为原点,每条边的松弛操作
for (int i = 0; i < G.V; i++)
{
foreach (var item in G.GetAdj(i))
{
if (dis[k, i] != int.MaxValue && dis[i, item] != int.MaxValue)
{
int temp = dis[k, i] + dis[i, item];
if (temp < dis[k, item])
{
dis[k, item] = temp;
}
}
}
}
}
}
//判断是否有负权环
for (int i = 0; i < G.V; i++)
{
if (dis[i, i] < 0)
{
hasNegCycle = true;
}
}
}
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;
}
}
}
}
}
