20140709

话说今天这个1个同学2002的题目真的有可总结性吗。

今天的结论是我的暴力又进化了，现在可以长达5KB，一节更比六节强。明天再来听评讲。

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
struct edge
{
	long long to,d;
	edge* next;
};
edge* head[5002],v[10004];
long long ne=0,n,x,y,w,s,n1,n2;
long long ca[5002][15],si1[5002],si2[5002],divv[5002];
long long de[5002],di[5002];
bool in[5002];
void ad(long long a,long long b,long long c)
{
	v[ne].to=b;
	v[ne].d=c;
	v[ne].next=head[a];
	head[a]=&v[ne];
	ne++;
}
void ss1(long long p)
{
	in[p]=true;
	divv[p]=1;
	n1++;
	si1[p]=1;
	for (edge* z=head[p];z!=NULL;z=z->next)
	{
		if (z->to!=-1 && in[z->to]==false)
		{
			ss1(z->to);
			si1[p]+=si1[z->to];
		}
	}
	return;
}
void ss2(long long q)
{
	in[q]=true;
	divv[q]=2;
	n2++;
	si2[q]=1;
	for (edge* z=head[q];z!=NULL;z=z->next)
	{
		if (z->to!=-1 && in[z->to]==false)
		{
			ss2(z->to);
			si2[q]+=si2[z->to];
		}
	}
	return;
}
void dfs1(long long p)
{
	in[p]=true;
	for (edge* z=head[p];z!=NULL;z=z->next)
	{
		if (z->to!=-1 && in[z->to]==false)
		{
			de[z->to]=de[p]+1;
			di[z->to]=di[p]+z->d;
			dfs1(z->to);
			ca[z->to][0]=p;
		}
	}
	return;
}
void dfs2(long long q)
{
	in[q]=true;
	for (edge* z=head[q];z!=NULL;z=z->next)
	{
		if (z->to!=-1 && in[z->to]==false)
		{
			de[z->to]=de[q]+1;
			di[z->to]=di[q]+z->d;
			dfs2(z->to);
			ca[z->to][0]=q;
		}
	}
	return;
}
long long lca(long long g,long long h)
{
	long long k;
	if (de[g]>de[h])
	{
		k=g;
		g=h;
		h=k;
	}
	for (int i=14;i>=0;i--)
	{
		if (de[ca[h][i]]>=de[g])
		{
			h=ca[h][i];
		}
	}
	if (g==h) return h;
	for (int i=14;i>=0;i--)
	{
		if (ca[g][i]!=ca[h][i])
		{
			g=ca[g][i];
			h=ca[h][i];
		}
	}
	return ca[h][0];
}






long long gogogo(long long p,long long q,long long y)
{
	long long ans=0;
	n1=0;
	n2=0;
	memset(ca,0,sizeof(ca));
	memset(si1,0,sizeof(si1));
	memset(si2,0,sizeof(si2));
	memset(divv,0,sizeof(divv));
	memset(in,false,sizeof(in));
	divv[p]=1;
	divv[q]=2;
	ss1(p);
	ss2(q);
	long long t1=0,o1=p,t2=0,o2=q;
	memset(in,false,sizeof(in));
	in[p]=true;
	in[q]=true;
	for (edge* z=head[p];z!=NULL;z=z->next)
	{
		if (z->to!=-1 && in[z->to]==false && si1[z->to]>t1)
		{
			t1=si1[z->to];
			o1=z->to;
		}
		if (z->to!=-1) in[z->to]=true;
	}
	while (2*t1>n1 && n1!=1)
	{
		p=o1;
		t1=0;
		for (edge* z=head[p];z!=NULL;z=z->next)
		{
			if (z->to!=-1 && in[z->to]==false && si1[z->to]>t1)
			{
				t1=si1[z->to];
				o1=z->to;
			}
			if (z->to!=-1) in[z->to]=true;
		}
	}
	for (edge* z=head[q];z!=NULL;z=z->next)
	{
		if (z->to!=-1 && in[z->to]==false && si2[z->to]>t2)
		{
			t2=si2[z->to];
			o2=z->to;
		}
		if (z->to!=-1) in[z->to]=true;
	}
	while (2*t2>n2 && n2!=1)
	{
		q=o2;
		t2=0;
		for (edge* z=head[q];z!=NULL;z=z->next)
		{
			if (z->to!=-1 && in[z->to]==false && si2[z->to]>t1)
			{
				t2=si2[z->to];
				o2=z->to;
			}
			if (z->to!=-1) in[z->to]=true;
		}
	}
	for (long long i=0;i<15;i++)
	{
		ca[p][i]=0;
		ca[q][i]=0;
	}
	memset(di,0,sizeof(di));
	memset(de,0,sizeof(de));
	memset(in,false,sizeof(in));
	dfs1(p);
	dfs2(q);
	for (long long i=1;i<15;i++)
	{
		for (long long j=1;j<=n;j++)
		{
			ca[j][i]=ca[ca[j][i-1]][i-1];
		}
	}
	long long u1=0,u2=0;
	for (long long i=1;i<n;i++)
	{
		for (long long j=i+1;j<=n;j++)
		{
			if (divv[i]==1 && divv[j]==1)
			{
				u1+=di[i]+di[j]-2*di[lca(i,j)];
			}
		}
	}
	for (long long i=1;i<n;i++)
	{
		for (long long j=i+1;j<=n;j++)
		{
			if (divv[i]==2 && divv[j]==2)
			{
				u2+=di[i]+di[j]-2*di[lca(i,j)];
			}
		}
	}
	ans+=n1*n2*y+u1+u2;
	u1=0;
	u2=0;
	for (long long i=1;i<=n;i++)
	{
		if (divv[i]==1)
		{
			u1+=di[i];
		}
		else
		{
			u2+=di[i];
		}
	}
	ans+=n1*u2+n2*u1;
	return ans;
}






int main()
{
	freopen("testA.in","r",stdin);
	freopen("testA.out","w",stdout);
	cin>>n;
	for (long long i=0;i<=n;i++)
	{
		head[i]=NULL;
	}
	for (long long i=1;i<n;i++)
	{
		cin>>x>>y>>w;
		ad(x,y,w);
		ad(y,x,w);
	}
	s=1000000000000000;
	for (long long i=1;i<n;i++)
	{
		long long l,r;
		r=v[i*2-2].to;
		l=v[i*2-1].to;
		v[i*2-2].to=-1;
		v[i*2-1].to=-1;
		s=min(s,gogogo(l,r,v[i*2-2].d));
		v[i*2-2].to=r;
		v[i*2-1].to=l;
	}
	cout<<s;
	return 0;
}

　　暴得一手好力