Networking（prim/ kruskal)

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最小生成树模板题

• prim算法

#include <iostream>
#include <cstring>
using namespace std;

const int N = 55, INF = 0x3f3f3f3f;
int g[N][N], dist[N];
bool vis[N];

int p, r;
int prim(){
	memset(dist, INF, sizeof dist);
	int res = 0, cnt = 0;
	for(int i = 0; i < p; i ++){
		int t = -1;
		for(int j = 1; j <= p; j ++)
			if(!vis[j] && (t == -1 || dist[t] > dist[j]))
				t = j;
		
		if(i) res += dist[t];
		
		for(int j = 1; j <= p; j ++)
			dist[j] = min(dist[j], g[t][j]);
		vis[t] = true;
	}
	return res;
}
int main(){
	while(cin >> p){
		if(p == 0)
			break;
		cin >> r;
		memset(vis, 0, sizeof vis);
		memset(g, INF, sizeof g);
		while(r --){
			int u, v, w;
			cin >> u >> v >> w;
			g[u][v] = g[v][u] = min(g[u][v], w);
		} 
		cout << prim() << endl;
	}
	
	
	return 0;
} 

//kruskal算法
#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;
const int N = 1000010;
struct Edge{
	int u, v, w, next;
}edge[N];
int n, m, fa[N];

bool cmp(Edge a, Edge b){
	return a.w < b.w;
}

int find(int x){
	if(x != fa[x])
		fa[x] = find(fa[x]);
	return fa[x];
}
int main(){
	while(cin >> n){
		if(n == 0)
			break;
		cin >> m;
		for(int i = 0; i < m; i ++){
			int u, v, w;
			cin >> u >> v >> w;
			edge[i].u = u;
			edge[i].v = v;
			edge[i].w = w;
		}
		sort(edge, edge + m, cmp);
		for(int i = 1; i <= n; i ++)
			fa[i] = i;
		int res = 0, cnt = 0;
		for(int i = 0; i < m; i ++){
			int a = edge[i].u, b = edge[i].v, w = edge[i].w;
			a = find(a), b = find(b);
			if(a != b){
				fa[a] = b;
				cnt ++;
				res += w;
			}
		}
		cout << res << endl;
	}
	
	return 0;
}