AcWing 858. Prim算法求最小生成树
原题链接
简单
作者:
想回家
,
2023-05-27 19:43:51
,
所有人可见
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阅读 159
#include<bits/stdc++.h>
using namespace std;
const int N=510,INF = 0x3f3f3f3f;
int n,m;
int g[N][N];
bool st[N];
int dis[N];
int Prim()
{
memset(dis,INF,sizeof dis);
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||dis[t]>dis[j]))
t = j;
}
if(i&&dis[t]==INF) return INF;
if(i) res+=dis[t];
for (int j = 1; j <= n; j++)
{
dis[j]=min(dis[j],g[t][j]);
}
st[t]=true;
}
return res;
}
int main()
{
scanf("%d%d",&n,&m);
memset(g,0x3f,sizeof g);
while (m--)
{
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
g[a][b]=g[b][a]=min(g[a][b],c);
}
int t = Prim();
if(t==INF) puts("impossible");
else printf("%d",t);
return 0;
}