Submission #2171834

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Source Code Expand

#include<cstdio>
#include<algorithm>
int n,m,fa[200005],num;
long long ans,d[200005];
long long min(long long a,long long b){return a<b?a:b;}
struct node{int u,v;long long w;}e[400005];
int find(int u)
{
	if(fa[u]==u)return u;
	return fa[u]=find(fa[u]);
}
bool comp(node a,node b){return a.w<b.w;}
int main()
{
	scanf("%d%d",&n,&m);
	for(int i=0;i<n;i++)d[i]=1e18;
	for(int i=1;i<=m;i++)
	{
		int x,y;long long z;
		scanf("%d%d%lld",&x,&y,&z);
		e[++num]=(node){x,y,z};
		d[x]=min(d[x],z+1);
		d[y]=min(d[y],z+2);
	}
	for(int t=0;t<2;t++)
	 for(int i=0;i<n;i++)
	  d[(i+1)%n]=min(d[i]+2,d[(i+1)%n]); 
	for(int i=0;i<n;i++)e[++num]=(node){i,(i+1)%n,d[i]},fa[i]=i;
	std::sort(e+1,e+1+num,comp);
	int t=0;
	for(int i=1;i<=num;i++)
	 if(find(e[i].u)!=find(e[i].v))
	 {
	 	fa[fa[e[i].u]]=fa[e[i].v];
	 	t++;ans+=e[i].w;if(t==n-1)break;
	 }
	printf("%lld\n",ans);
}

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Judge Result