【题解】
答案就是总的边权和减去最小生成树上的边权和。
1 #include<cstdio> 2 #include<algorithm> 3 #include<cstring> 4 #define LL long long 5 #define rg register 6 #define N 200010 7 using namespace std; 8 int n,m,sum,ans,cnt,f[N]; 9 struct edge{ 10 int u,v,dis; 11 }a[N]; 12 inline int read(){ 13 int k=0,f=1; char c=getchar(); 14 while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar(); 15 while('0'<=c&&c<='9')k=k*10+c-'0',c=getchar(); 16 return k*f; 17 } 18 inline bool cmp(edge a,edge b){return a.dis<b.dis;} 19 inline int find(int x){return f[x]==x?x:f[x]=find(f[x]);} 20 int main(){ 21 n=read(); m=read(); 22 for(rg int i=1;i<=m;i++) a[i].u=read(),a[i].v=read(),sum+=(a[i].dis=read()); 23 sort(a+1,a+1+m,cmp); 24 for(rg int i=1;i<=n;i++) f[i]=i; 25 for(rg int i=1;i<=m;i++){ 26 int u=find(a[i].u),v=find(a[i].v); 27 if(u!=v){ 28 ans+=a[i].dis; f[u]=v; cnt++; 29 } 30 if(cnt==n-1) break; 31 } 32 printf("%d ",sum-ans); 33 return 0; 34 }