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; } } } } }