2023-9-2 Prim算法求最小生成树

题目链接：Prim算法求最小生成树

#include <iostream>
#include <cstring>
#include <algorithm>using namespace std;const int N = 510, INF = 0x3f3f3f3f;int n, m;
int g[N][N];
int dist[N];
bool st[N];int prim()
{memset(dist, 0x3f, sizeof dist);int res = 0;for(int i = 0; i < n; i++){int t = -1;for(int j = 1; j <= n; j++)if(!st[j] && (t == -1 || dist[t] > dist[j]))t = j;if(i && dist[t] == INF) return INF;if(i) res += dist[t];for(int j = 1; j <= n; j ++) dist[j] = min(dist[j], g[t][j]);st[t] = true;}return res;
}int main()
{cin >> n >> m;memset(g, 0x3f, sizeof g);for(int i = 0; i < m; i++){int a, b, c;cin >> a >> b >> c;g[a][b] = g[b][a] = min(g[a][b], c);}int t = prim();if(t == INF) cout << "impossible" << endl;else cout << t << endl;return 0;
}