mirror of
https://git.sb/baoshuo/OI-codes.git
synced 2024-12-13 08:46:27 +00:00
43 lines
938 B
C++
43 lines
938 B
C++
#include <bits/stdc++.h>
|
|
|
|
using namespace std;
|
|
|
|
int n, m, u, v, w, g[505][505], dist[505];
|
|
bool vis[505];
|
|
|
|
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 (!vis[j] && (t == -1 || dist[j] < dist[t])) {
|
|
t = j;
|
|
}
|
|
}
|
|
if (i && dist[t] == 0x3f3f3f3f) return 0x3f3f3f3f;
|
|
if (i) res += dist[t];
|
|
for (int j = 1; j <= n; j++) {
|
|
dist[j] = min(dist[j], g[t][j]);
|
|
}
|
|
vis[t] = true;
|
|
}
|
|
return res;
|
|
}
|
|
|
|
int main() {
|
|
cin >> n >> m;
|
|
memset(g, 0x3f, sizeof(g));
|
|
for (int i = 0; i < m; i++) {
|
|
cin >> u >> v >> w;
|
|
g[u][v] = g[v][u] = min(g[u][v], w);
|
|
}
|
|
int ans = prim();
|
|
if (ans == 0x3f3f3f3f) {
|
|
cout << "impossible" << endl;
|
|
} else {
|
|
cout << ans << endl;
|
|
}
|
|
return 0;
|
|
}
|