Submission #3561919

---

Source Code Expand

#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#define RG register
#define LL long long
using namespace std;
const int N=2e5+10;
struct node{ int a,b; LL c; }pt[N];
int n,m,cnt,tot,fa[N];
LL minn[N],ans;
inline bool cmp(node a,node b){return a.c<b.c;}
inline int read(){
	char ch=getchar(); int x=0, f=1;
	while(ch<'0' || ch>'9'){if(ch=='-') f=-1; ch=getchar();	}
	while(ch>='0' && ch<='9'){x=x*10+ch-'0'; ch=getchar();	}
	return x*f;}
inline LL mi(LL a,LL b){return a<b ? a : b;}
inline int f(int son){return fa[son]= fa[son]==son ? son : f(fa[son]);}
int main()
{
	//freopen("Zigzag MST.in","r",stdin);
	//freopen(".out","w",stdout);
	n=read(); m=read();
	memset(minn,0x3f,sizeof minn);
	for(int i=0;i<n;i++) fa[i]=i;
	for(int i=1,a,b,c;i<=m;i++)
	{
		a=read()%n; b=read()%n; c=read();
		pt[++cnt]={a,b,c};
		minn[a]=mi(minn[a],c+1);
		minn[b]=mi(minn[b],c+2);
	}
	for(int i=1;i<2*n;i++) minn[i%n]=mi(minn[i%n],minn[(i-1)%n]+2);
	for(int i=0;i<n;i++) pt[++cnt]=(node){i%n,(i+1)%n,minn[i]};
	sort(pt+1,pt+1+cnt,cmp);
	for(int i=1;i<=cnt;i++)
	{
		int fx=f(pt[i].a), fy=f(pt[i].b);
		if(fx==fy) continue;
		fa[fx]=fy;
		ans+=pt[i].c;
		if(++tot==n-1) return printf("%lld\n",ans), 0;
	}
	//fclose(stdin); fclose(stdout);
	return 0;
}

Submission Info

Judge Result