有向图的欧拉回路

Author: Dev-XYS

Eulerian-Tour(Digraph).cpp

@@ -0,0 +1,112 @@
+#include <cstdio>
+
+#define NIL 0
+
+using namespace std;
+
+struct vertex
+{
+	int first, ideg, odeg;
+	bool vis;
+}V[100010];
+
+struct edge
+{
+	int op, endp, next;
+}E[200010];
+
+int ec = 1, ivc, iec, cnt = 0;
+int path[200010], pc;
+
+void add_edge(int u, int v)
+{
+	V[u].odeg++;
+	V[v].ideg++;
+	E[ec].next = V[u].first;
+	V[u].first = ec;
+	E[ec].op = u;
+	E[ec].endp = v;
+	ec++;
+}
+
+void del_edge(int ord)
+{
+	V[E[ord].op].first = E[ord].next;
+}
+
+void connect(int u)
+{
+	if (V[u].vis == false)
+	{
+		cnt++;
+		V[u].vis = true;
+		for (int cur = V[u].first; cur != 0; cur = E[cur].next)
+		{
+			connect(E[cur].endp);
+		}
+	}
+}
+
+void DFS(int u, int start)
+{
+	int first = V[u].first;
+	del_edge(first);
+	if (E[first].endp != start)
+	{
+		DFS(E[first].endp, start);
+	}
+	path[pc++] = first;
+	while (V[u].first != NIL)
+	{
+		DFS(u, u);
+	}
+}
+
+int main()
+{
+	int k, u, v;
+	scanf("%d%d%d", &k, &ivc, &iec);
+	for (int i = 0; i < iec; i++)
+	{
+		scanf("%d%d", &u, &v);
+		add_edge(u, v);
+	}
+	for (int i = 1; i <= ivc; i++)
+	{
+		if (V[i].ideg != V[i].odeg)
+		{
+			printf("NO");
+			return 0;
+		}
+		if (V[i].ideg == 0)
+		{
+			cnt++;
+		}
+	}
+	int vhe;
+	for (int i = 1; i <= ivc; i++)
+	{
+		if (V[i].ideg != 0)
+		{
+			connect(i);
+			vhe = i;
+			break;
+		}
+	}
+	if (cnt < ivc)
+	{
+		printf("NO");
+		return 0;
+	}
+	printf("YES\n");
+	if (iec == 0)
+	{
+		return 0;
+	}
+	DFS(vhe, vhe);
+	for (int i = pc - 1; i >= 0; i--)
+	{
+		printf("%d ", path[i]);
+	}
+	return 0;
+}