UVA-10600 ACM Contest and Blackout （次小生成树）

# include<iostream>
# include<cstdio>
# include<cstring>
# include<cstring>
using namespace std;
# define REP(i,s,n) for(int i=s;i<n;++i)
# define CL(a,b) memset(a,b,sizeof(a))
# define CLL(a,b,n) fill(a,a+n,b)

const int N=105;
const int INF=1<<30;
int n,m,dis
,dp

,G

,G1

,vis
;

int prim()
{
REP(i,0,n) REP(j,i,n) G1[i][j]=G1[j][i]=INF;
CLL(dis,INF,n);
CL(vis,0);
REP(i,0,n) dis[i]=G[0][i];
dis[0]=0;
vis[0]=1;
int res=0;
REP(k,1,n){
int minn=INF,u;
REP(i,0,n) if(!vis[i]&&minn>dis[i]){
minn=dis[i];
u=i;
}
res+=dis[u];
vis[u]=1;
REP(i,0,n) if(vis[i]&&G[i][u]==dis[u]){
G1[i][u]=G1[u][i]=dis[u];
break;
}
REP(i,0,n) if(!vis[i]&&dis[i]>G[u][i])
dis[i]=G[u][i];
}
return res;
}

void dfs(int rt,int u,int w)
{
if(dp[rt][u]!=-1) return ;
dp[rt][u]=w;
REP(i,0,n) if(G1[u][i]!=INF)
dfs(rt,i,max(w,G1[u][i]));
}

int main()
{
int T,a,b,c;
scanf("%d",&T);
while(T--)
{
scanf("%d%d",&n,&m);
REP(i,0,n) REP(j,i,n) G[i][j]=G[j][i]=INF;
while(m--)
{
scanf("%d%d%d",&a,&b,&c);
--a,--b;
G[a][b]=G[b][a]=c;
}
int MST=prim();
CL(dp,-1);
REP(i,0,n) dfs(i,i,0);
int MST1=INF;
REP(i,0,n) REP(j,i+1,n){
if(G[i][j]==INF||G1[i][j]<INF||G[i][j]<dp[i][j]) continue;
MST1=min(MST1,MST-dp[i][j]+G[i][j]);
}
printf("%d %d\n",MST,MST1);
}
return 0;
}