AC日记——[SDOI2011]染色 洛谷 P2486

#include <cstdio>
#include <iostream>
#include <algorithm>

#define maxn 200001

using namespace std;

struct TreeNodeType {
    int l,r,dis,lc,rc,flag,mid;
};
struct TreeNodeType tree[maxn<<2];

struct EdgeType {
    int to,next;
};
struct EdgeType edge[maxn<<1];

int n,m,if_z,dis[maxn],flag[maxn],dis_[maxn];
int size[maxn],head[maxn],deep[maxn],f[maxn];
int cnt,tot,num,belong[maxn];

char Cget;

inline void read_int(int &now)
{
    now=0,if_z=1,Cget=getchar();
    while(Cget>‘9‘||Cget<‘0‘)
    {
        if(Cget==‘-‘) if_z=-1;
        Cget=getchar();
    }
    while(Cget>=‘0‘&&Cget<=‘9‘)
    {
        now=now*10+Cget-‘0‘;
        Cget=getchar();
    }
    now*=if_z;
}

inline void edge_add(int from,int to)
{
    edge[++num].to=from,edge[num].next=head[to],head[to]=num;
    edge[++num].to=to,edge[num].next=head[from],head[from]=num;
}

void search(int now,int fa)
{
    int pos=cnt++;
    deep[now]=deep[fa]+1,f[now]=fa;
    for(int i=head[now];i;i=edge[i].next)
    {
        if(edge[i].to==fa) continue;
        search(edge[i].to,now);
    }
    size[now]=cnt-pos;
}

void search_(int now,int chain)
{
    belong[now]=chain,flag[now]=++cnt;
    dis_[flag[now]]=dis[now];
    int pos=0;
    for(int i=head[now];i;i=edge[i].next)
    {
        if(edge[i].to==f[now]) continue;
        if(size[edge[i].to]>size[pos]) pos=edge[i].to;
    }
    if(pos!=0) search_(pos,chain);
    else return ;
    for(int i=head[now];i;i=edge[i].next)
    {
        if(edge[i].to==f[now]||edge[i].to==pos) continue;
        search_(edge[i].to,edge[i].to);
    }
}

inline void tree_up(int now)
{
    if(tree[now<<1].rc==tree[now<<1|1].lc)
    {
        tree[now].dis=tree[now<<1].dis+tree[now<<1|1].dis-1;
    }
    else
    {
        tree[now].dis=tree[now<<1].dis+tree[now<<1|1].dis;
    }
    tree[now].lc=tree[now<<1].lc,tree[now].rc=tree[now<<1|1].rc;
}

inline void tree_down(int now)
{
    if(tree[now].l==tree[now].r) return ;
    tree[now<<1].dis=1,tree[now<<1|1].dis=1;
    tree[now<<1].lc=tree[now<<1].rc=tree[now].flag;
    tree[now<<1|1].lc=tree[now<<1|1].rc=tree[now].flag;
    tree[now<<1].flag=tree[now<<1|1].flag=tree[now].flag;
    tree[now].flag=0;
}

void tree_build(int now,int l,int r)
{
    tree[now].l=l,tree[now].r=r;
    if(l==r)
    {
        tree[now].lc=dis_[++cnt];
        tree[now].rc=tree[now].lc;
        tree[now].dis=1;
        return ;
    }
    tree[now].mid=(l+r)>>1;
    tree_build(now<<1,l,tree[now].mid);
    tree_build(now<<1|1,tree[now].mid+1,r);
    tree_up(now);
}

void tree_change(int now,int l,int r,int x)
{
    if(tree[now].l==l&&tree[now].r==r)
    {
        tree[now].dis=1,tree[now].flag=x;
        tree[now].lc=tree[now].rc=x;
        return ;
    }
    if(tree[now].flag) tree_down(now);
    if(l>tree[now].mid) tree_change(now<<1|1,l,r,x);
    else if(r<=tree[now].mid) tree_change(now<<1,l,r,x);
    else
    {
        tree_change(now<<1,l,tree[now].mid,x);
        tree_change(now<<1|1,tree[now].mid+1,r,x);
    }
    tree_up(now);
}

int tree_query(int now,int l,int r)
{
    if(tree[now].l==l&&tree[now].r==r)
    {
        return tree[now].dis;
    }
    if(tree[now].flag) tree_down(now);
    tree_up(now);
    if(l>tree[now].mid) return tree_query(now<<1|1,l,r);
    else if(r<=tree[now].mid) return tree_query(now<<1,l,r);
    else
    {
        int ld=tree_query(now<<1,l,tree[now].mid);
        int rd=tree_query(now<<1|1,tree[now].mid+1,r);
        if(tree[now<<1].rc==tree[now<<1|1].lc) return ld+rd-1;
        else return ld+rd;
    }
}

int tree_query_color(int now,int to)
{
    if(tree[now].l==tree[now].r&&tree[now].l==to)
    {
        return tree[now].lc;
    }
    if(tree[now].flag) tree_down(now);
    tree_up(now);
    if(to>tree[now].mid) return tree_query_color(now<<1|1,to);
    else return tree_query_color(now<<1,to);
}

inline void solve_change(int x,int y,int z)
{
    while(belong[x]!=belong[y])
    {
        if(deep[belong[x]]<deep[belong[y]]) swap(x,y);
        tree_change(1,flag[belong[x]],flag[x],z);
        x=f[belong[x]];
    }
    tree_change(1,min(flag[x],flag[y]),max(flag[x],flag[y]),z);
}

inline int solve_query(int x,int y)
{
    int ans=0;
    while(belong[x]!=belong[y])
    {
        if(deep[belong[x]]<deep[belong[y]]) swap(x,y);
        ans+=tree_query(1,flag[belong[x]],flag[x]);
        if(tree_query_color(1,flag[belong[x]])==tree_query_color(1,flag[f[belong[x]]])) ans--;
        x=f[belong[x]];
    }
    ans+=tree_query(1,min(flag[x],flag[y]),max(flag[x],flag[y]));
    return ans;
}

int main()
{
    read_int(n),read_int(m);
    for(int i=1;i<=n;i++) read_int(dis[i]);
    int from,to,pos;
    for(int i=1;i<n;i++)
    {
        read_int(from),read_int(to);
        edge_add(from,to);
    }
    search(1,0),cnt=0,search_(1,1),cnt=0,tree_build(1,1,n);
    char type;
    for(int i=1;i<=m;i++)
    {
        cin>>type;
        if(type==‘C‘)
        {
            read_int(from),read_int(to),read_int(pos);
            solve_change(from,to,pos);
        }
        else
        {
            read_int(from),read_int(to);
            printf("%d\n",solve_query(from,to));
        }
    }
    return 0;
}