UOJ 274 【清华集训2016】温暖会指引我们前行 ——Link-Cut Tree

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
#define F(i,j,k) for (int i=j;i<=k;++i)
#define D(i,j,k) for (int i=j;i>=k;--i)
#define maxn 1000005
#define inf 0x3f3f3f3f
struct Link_Cut_Tree{
	int ch[maxn][2],fa[maxn],rev[maxn],mn[maxn],val[maxn],sum[maxn],len[maxn];
	int sta[maxn],top;
	bool isroot(int x){return ch[fa[x]][0]!=x&&ch[fa[x]][1]!=x;}
	void update(int x)
	{
		mn[x]=x;
		if (val[mn[ch[x][0]]]<val[mn[x]]) mn[x]=mn[ch[x][0]];
		if (val[mn[ch[x][1]]]<val[mn[x]]) mn[x]=mn[ch[x][1]];
		sum[x]=len[x]+sum[ch[x][0]]+sum[ch[x][1]];
	}
	void pushdown (int x)
	{
		if (rev[x])
		{
			rev[x]^=1;
			rev[ch[x][0]]^=1;
			rev[ch[x][1]]^=1;
			swap(ch[x][0],ch[x][1]);
		}
	}
	void rot(int x)
	{
		int y=fa[x],z=fa[y],l,r;
		if (ch[y][0]==x) l=0; else l=1; r=l^1;
		if (!isroot(y))
		{
			if (ch[z][0]==y) ch[z][0]=x;
			else ch[z][1]=x;
		}
		fa[x]=z; fa[y]=x; fa[ch[x][r]]=y;
		ch[y][l]=ch[x][r]; ch[x][r]=y;
		update(y);update(x);
	}
	void splay(int x)
	{
		top=0;sta[++top]=x;
		for (int i=x;!isroot(i);i=fa[i]) sta[++top]=fa[i];
		while (top) pushdown(sta[top--]);
		
		while (!isroot(x))
		{
			int y=fa[x],z=fa[y];
			if (!isroot(y))
			{
				if (ch[z][0]==y^ch[y][0]==x) rot(x);
				else rot(y);
			}
			rot(x);
		}
	}
	void access(int x)
	{
		for (int t=0;x;t=x,x=fa[x])
			splay(x),ch[x][1]=t,update(x);
	}
	void makeroot(int x)
	{
		access(x); splay(x); rev[x]^=1;
	}
	int find(int x)
	{
		access(x); splay(x); while (ch[x][0]) x=ch[x][0];
		return x;
	}
	void link(int x,int y)
	{
		makeroot(x);
		fa[x]=y;
	}
	void cut(int x,int y)
	{
		makeroot(x);
		access(y);
		ch[y][0]=0;
		fa[x]=0;
	}
	int query(int x,int y)
	{
		if (find(x)!=find(y)) return -1;
		makeroot(x);access(y);splay(y);
		return sum[y];
	}
	int qmn(int x,int y)
	{
		makeroot(x);access(y);splay(y);
		return mn[y];
	}
	void modify(int x,int l)
	{
		access(x);splay(x);
		len[x]=l;update(x);
	}
}LCT;

int n,m,u[maxn],v[maxn],id,t,l,x,y,in[maxn];
char opt[11];

int main()
{
	scanf("%d%d",&n,&m);
	F(i,0,n) LCT.val[i]=inf;
	F(i,1,m)
	{
		scanf("%s",opt);
		switch(opt[0])
		{
			case ‘f‘:
				scanf("%d",&id); id++;
				scanf("%d%d%d%d",&u[id],&v[id],&t,&l);u[id]++;v[id]++;
				LCT.len[id+n]=l;LCT.val[id+n]=t;LCT.mn[id+n]=id+n;
				if (LCT.find(u[id])!=LCT.find(v[id]))
				{
					LCT.link(id+n,u[id]);
					LCT.link(id+n,v[id]);
					in[id]=1;
				}
				else
				{
					int tmp=LCT.qmn(u[id],v[id]);
					if (LCT.val[tmp]<t)
					{
						LCT.cut(u[tmp-n],tmp);
						LCT.cut(v[tmp-n],tmp);
						in[tmp-n]=0;
						LCT.link(id+n,u[id]);
						LCT.link(id+n,v[id]);
						in[id]=1;
					}
				}
			break;
			case ‘m‘:
				scanf("%d%d",&x,&y);x++;y++;
				printf("%d\n",LCT.query(x,y));
			break;
			case ‘c‘:
				scanf("%d%d",&id,&l); id++;
				if (in[id]) LCT.modify(id+n,l);
			break; 
		}
	}
}