bzoj2243 [SDOI2011]染色

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<queue>
#include<deque>
#include<set>
#include<map>
#include<ctime>
#define LL long long
#define inf 0x7ffffff
#define pa pair<int,int>
#define pi 3.1415926535897932384626433832795028841971
#define N 100010
using namespace std;
inline LL read()
{
	LL x=0,f=1;char ch=getchar();
	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;
}
int n,m,cnt,tt,save_lc,save_rc,mn,mx;
struct edge{
	int to,next;
}e[2*N];
struct segtree{
	int l,r,sum,lc,rc,tag;
}tree[4*N];
int head[N],v[N];
int mrk[N],son[N],depth[N],fa[N][21];
int place[N],pplace[N],belong[N];
char ch[10];
inline void ins(int u,int v)
{
	e[++cnt].to=v;
	e[cnt].next=head[u];
	head[u]=cnt;
}
inline void insert(int u,int v)
{
	ins(u,v);
	ins(v,u);
}
inline void dfs1(int x,int dep)
{
	if (mrk[x])return;
	mrk[x]=1;son[x]=1;depth[x]=dep;
	for (int i=1;i<20;i++) fa[x][i]=fa[fa[x][i-1]][i-1];
	for (int i=head[x];i;i=e[i].next)
	if (!mrk[e[i].to])
	{
		fa[e[i].to][0]=x;
		dfs1(e[i].to,dep+1);
		son[x]+=son[e[i].to];
	}
}
inline void dfs2(int x,int chain)
{
	place[x]=++tt;pplace[tt]=x;
	belong[x]=chain;
	int mx=-inf,res=-1;
	for (int i=head[x];i;i=e[i].next)
	if (e[i].to!=fa[x][0])
	{
		if (son[e[i].to]>mx)
		{
			mx=son[e[i].to];
			res=e[i].to;
		}
	}
	if (res==-1)return;
	dfs2(res,chain);
	for(int i=head[x];i;i=e[i].next)
	if (e[i].to!=fa[x][0]&&e[i].to!=res)
		dfs2(e[i].to,e[i].to);
}
inline int LCA(int a,int b)
{
	if (depth[a]<depth[b])swap(a,b);
	int res=depth[a]-depth[b];
	for (int i=0;i<20;i++)
		if (res & (1<<i))a=fa[a][i];
	for (int i=19;i>=0;i--)
	if (fa[a][i]!=fa[b][i])
	{
		a=fa[a][i];
		b=fa[b][i];
	}
	if(a==b)return a;
	return fa[a][0];
}
inline void update(int k)
{
	tree[k].lc=tree[k<<1].lc;
	tree[k].rc=tree[k<<1|1].rc;
	tree[k].sum=tree[k<<1].sum+tree[k<<1|1].sum;
	if (tree[k<<1].rc==tree[k<<1|1].lc)tree[k].sum--;
}
inline void pushdown(int k)
{
	int tag=tree[k].tag;tree[k].tag=-1;
	if (tag==-1||tree[k].l==tree[k].r)return;
	tree[k<<1].tag=tree[k<<1|1].tag=tag;
	tree[k<<1].sum=tree[k<<1|1].sum=1;
	tree[k<<1].lc=tree[k<<1|1].lc=tag;
	tree[k<<1].rc=tree[k<<1|1].rc=tag;
}
inline void buildtree(int now,int l,int r)
{
	tree[now].l=l;tree[now].r=r;
	tree[now].tag=-1;
	if (l==r)
	{
		tree[now].lc=v[pplace[l]];
		tree[now].rc=v[pplace[l]];
		tree[now].sum=1;
		return;
	}
	int mid=(l+r)>>1;
	buildtree(now<<1,l,mid);
	buildtree(now<<1|1,mid+1,r);
	update(now);
}
inline int ask_in_tree(int now,int x,int y)
{
	pushdown(now);
	int l=tree[now].l,r=tree[now].r;
	if (l==x&&r==y)
	{
		if (l<mn)
		{
			save_lc=tree[now].lc;
			mn=l;
		}
		if (r>mx)
		{
			save_rc=tree[now].rc;
			mx=r;
		}
		return tree[now].sum;
	}
	int mid=(l+r)>>1;
	if (y<=mid)return ask_in_tree(now<<1,x,y);
	if (x>mid)return ask_in_tree(now<<1|1,x,y);
	else
	{
		int res=ask_in_tree(now<<1,x,mid)+ask_in_tree(now<<1|1,mid+1,y);
		if (tree[now<<1].rc==tree[now<<1|1].lc)res--;
		return res;
	}
}
inline void change_in_tree(int now,int x,int y,int dat)
{
	pushdown(now);
	int l=tree[now].l,r=tree[now].r;
	if (l==x&&r==y)
	{
		tree[now].lc=tree[now].rc=dat;
		tree[now].sum=1;
		tree[now].tag=dat;
		return;
	}
	int mid=(l+r)>>1;
	if (y<=mid)change_in_tree(now<<1,x,y,dat);
	else if (x>mid)change_in_tree(now<<1|1,x,y,dat);
	else
	{
		change_in_tree(now<<1,x,mid,dat);
		change_in_tree(now<<1|1,mid+1,y,dat);
	}
	update(now);
}
inline int ask(int from,int to)
{
	int l,r,s=0,last=-1;
	while (belong[from]!=belong[to])
	{
		l=place[belong[from]];
		r=place[from];
		mx=-inf;mn=inf;save_lc=save_rc=-1;
		s+=ask_in_tree(1,l,r);
		if (last!=-1&&last==save_rc)s--;
		last=save_lc;
		from=fa[belong[from]][0];
	}
	l=place[to];
	r=place[from];
	mx=-inf;mn=inf;save_lc=save_rc=-1;
	s+=ask_in_tree(1,l,r);
	if (last!=-1&&last==save_rc)s--;
	return s;
}
inline void change(int from,int to,int dat)
{
	int l,r;
	while (belong[from]!=belong[to])
	{
		l=place[belong[from]];
		r=place[from];
		change_in_tree(1,l,r,dat);
		from=fa[belong[from]][0];
	}
	l=place[to];
	r=place[from];
	change_in_tree(1,l,r,dat);
}
int main()
{
	n=read();m=read();
	for(int i=1;i<=n;i++)v[i]=read();
	for (int i=1;i<n;i++)
	{
		int x=read(),y=read();
		insert(x,y);
	}
	dfs1(1,1);
	dfs2(1,1);
	buildtree(1,1,n);
	for (int i=1;i<=m;i++)
	{
		scanf("%s",ch);
		if (ch[0]==‘Q‘)
		{
			int x=read(),y=read(),lca=LCA(x,y);
			printf("%d\n",ask(x,lca)+ask(y,lca)-1);
		}
		if (ch[0]==‘C‘)
		{
			int x=read(),y=read(),z=read(),lca=LCA(x,y);
			change(x,lca,z);
			change(y,lca,z);
		}
	}
	return 0;
}