最小生成树Prim算法

Author: Dev-XYS

Prim.cpp

@@ -0,0 +1,78 @@
+#include <cstdio>
+#include <queue>
+
+typedef long long ll;
+
+using namespace std;
+
+struct vertex
+{
+	int first;
+}V[5010];
+
+struct edge
+{
+	int endp, next, w;
+}E[400010];
+
+struct queue_node
+{
+	int u;
+	ll dis;
+	queue_node(int _u = 0, ll _dis = 0) : u(_u), dis(_dis) { }
+};
+
+int n, m, ec = 2;
+bool vis[5010];
+
+inline void add_edge(int u, int v, int w)
+{
+	E[ec].next = V[u].first;
+	V[u].first = ec;
+	E[ec].endp = v;
+	E[ec].w = w;
+	ec++;
+}
+
+inline bool operator < (const queue_node &x, const queue_node &y)
+{
+	return x.dis > y.dis;
+}
+
+ll prim()
+{
+	ll res = 0;
+	int vc = 0;
+	priority_queue<queue_node> Q;
+	Q.push(queue_node(1, 0));
+	while (vc < n)
+	{
+		queue_node u = Q.top();
+		Q.pop();
+		if (vis[u.u] == false)
+		{
+			res += u.dis;
+			vis[u.u] = true;
+			vc++;
+			for (int cur = V[u.u].first; cur != 0; cur = E[cur].next)
+			{
+				Q.push(queue_node(E[cur].endp, E[cur].w));
+			}
+		}
+	}
+	return res;
+}
+
+int main()
+{
+	scanf("%d%d", &n, &m);
+	int u, v, w;
+	for (int i = 0; i < m; i++)
+	{
+		scanf("%d%d%d", &u, &v, &w);
+		add_edge(u, v, w);
+		add_edge(v, u, w);
+	}
+	printf("%lld\n", prim());
+	return 0;
+}