Constructing Roads

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• 一道最小生成树的模板题

刚开始建好图之后，后续再进行输入已经建好的路时，同时更新一下，且该路的权值为0.

//prim算法
#include <iostream>
#include <cstring>

using namespace std;

const int N = 105, INF = 0x3f3f3f3f;
int n, g[N][N], vis[N], dist[N], res;

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