[BZOJ1984] 月下“毛景树”|树链剖分|线段树

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<vector>
#include<set>
#include<map>
#include<queue>
#define N 100005
using namespace std;
int head[N],next[2*N],list[2*N],key[2*N];
int l[4*N],r[4*N],tagadd[4*N],tagchange[4*N],size[N],mx[4*N],c[N],fa[N][20],deep[N],id[N],belong[N];
int n,cnt,dfn;
struct node {int u,v,w;} e[N];
char ch[10];
inline int read()
{
    int a=0,f=1; char c=getchar();
    while (c<‘0‘||c>‘9‘) {if (c==‘-‘) f=-1; c=getchar();}
    while (c>=‘0‘&&c<=‘9‘) {a=a*10+c-‘0‘; c=getchar();}
    return a*f;
}
inline void insert(int x,int y,int z)
{
    next[++cnt]=head[x];
    head[x]=cnt;
    list[cnt]=y;
    key[cnt]=z;
}
void dfs1(int x)
{
    size[x]=1;
    for (int i=1;(1<<i)<=deep[x];i++) fa[x][i]=fa[fa[x][i-1]][i-1];
    for (int i=head[x];i;i=next[i])
    {
        if (list[i]==fa[x][0]) continue;
        fa[list[i]][0]=x;
        c[list[i]]=key[i];
        deep[list[i]]=deep[x]+1;
        dfs1(list[i]);
        size[x]+=size[list[i]];
    }
}
void dfs2(int x,int chain)
{
    belong[x]=chain;
    id[x]=++dfn;
    int k=0;
    for (int i=head[x];i;i=next[i])
        if (list[i]!=fa[x][0]&&size[list[i]]>size[k]) k=list[i];
    if (!k) return;
    dfs2(k,chain);
    for (int i=head[x];i;i=next[i])
        if (list[i]!=fa[x][0]&&list[i]!=k) dfs2(list[i],list[i]);
}
inline int lca(int x,int y)
{
    if (deep[x]<deep[y]) swap(x,y);
    int t=deep[x]-deep[y];
    for (int i=0;(1<<i)<=t;i++)
        if ((1<<i)&t) x=fa[x][i];
    for (int i=18;i>=0;i--)
        if (fa[x][i]!=fa[y][i]) {x=fa[x][i]; y=fa[y][i];}
    return x==y?x:fa[x][0];
}
void build(int k,int x,int y)
{
    l[k]=x; r[k]=y; tagchange[k]=-1;
    if (x==y) return;
    int mid=(x+y)>>1;
    build(k<<1,x,mid); build(k<<1|1,mid+1,y);
}
inline void pushup(int k)
{
    mx[k]=max(mx[k<<1],mx[k<<1|1]);
}
inline void pushdown(int k)
{
    if (l[k]==r[k]) return;
    if (tagchange[k]!=-1)
    {
        tagadd[k<<1]=tagadd[k<<1|1]=0;
        tagchange[k<<1]=tagchange[k<<1|1]=tagchange[k];
        mx[k<<1]=mx[k<<1|1]=tagchange[k];
        tagchange[k]=-1;
    }
    if (tagadd[k])
    {
        mx[k<<1]+=tagadd[k]; mx[k<<1|1]+=tagadd[k];
        if (tagchange[k<<1]!=-1) tagchange[k<<1]+=tagadd[k]; else tagadd[k<<1]+=tagadd[k];
        if (tagchange[k<<1|1]!=-1) tagchange[k<<1|1]+=tagadd[k]; else tagadd[k<<1|1]+=tagadd[k];
        tagadd[k]=0;
    }
}
void change(int k,int x,int y,int v)
{
    pushdown(k);
    if (l[k]==x&&r[k]==y)
    {
        tagchange[k]=mx[k]=v;
        return;
    }
    int mid=(l[k]+r[k])>>1;
    if (y<=mid) change(k<<1,x,y,v);
    else if (x>mid) change(k<<1|1,x,y,v);
    else 
    {
        change(k<<1,x,mid,v);
        change(k<<1|1,mid+1,y,v);
    }
    pushup(k);
}
void add(int k,int x,int y,int v)
{
    pushdown(k);
    if (l[k]==x&&r[k]==y)
    {
        tagadd[k]=v;
        mx[k]+=v;
        return;
    }
    int mid=(l[k]+r[k])>>1;
    if (y<=mid) add(k<<1,x,y,v);
    else if (x>mid) add(k<<1|1,x,y,v);
    else
    {
        add(k<<1,x,mid,v);
        add(k<<1|1,mid+1,y,v);
    }
    pushup(k);
}
int getmx(int k,int x,int y)
{
    pushdown(k);
    if (l[k]==x&&r[k]==y) return mx[k];
    int mid=(l[k]+r[k])>>1;
    if (mid>=y) return getmx(k<<1,x,y);
    else if (mid<x)return getmx(k<<1|1,x,y);
    else return max(getmx(k<<1,x,mid),getmx(k<<1|1,mid+1,y));
}
inline void solvechange(int x,int f,int w)
{
    if (x==f) return;
    while (belong[x]!=belong[f])
    {
        change(1,id[belong[x]],id[x],w);
        x=fa[belong[x]][0];
    }
    if (x==f) return; int k=0;
    for (int i=head[f];i;i=next[i])
        if (list[i]!=fa[f][0]&&fa[lca(list[i],x)][0]==f) k=list[i];
    change(1,id[k],id[x],w);
}
inline int solvemax(int x,int f)
{
    if (x==f) return -1;
    int ans=-1;
    while (belong[x]!=belong[f])
    {
        ans=max(ans,getmx(1,id[belong[x]],id[x]));
        x=fa[belong[x]][0];
    }
    if (x==f) return ans; int k=0;
    for (int i=head[f];i;i=next[i])
        if (list[i]!=fa[f][0]&&fa[lca(list[i],x)][0]==f) k=list[i];
    return max(ans,getmx(1,id[k],id[x]));
}
inline void solveadd(int x,int f,int w)
{
    if (x==f) return;
    while (belong[x]!=belong[f])
    {
        add(1,id[belong[x]],id[x],w);
        x=fa[belong[x]][0];
    }
    if (x==f) return; int k=0;
    for (int i=head[f];i;i=next[i])
        if (list[i]!=fa[f][0]&&fa[lca(list[i],x)][0]==f) k=list[i];
    add(1,id[k],id[x],w);
}
int main()
{
    n=read();
    for (int i=1;i<n;i++)
    {
        e[i].u=read(),e[i].v=read(),e[i].w=read();
        insert(e[i].u,e[i].v,e[i].w); insert(e[i].v,e[i].u,e[i].w);
    }
    dfs1(1); dfs2(1,1); build(1,1,n);    
    for (int i=1;i<=n;i++) change(1,id[i],id[i],c[i]);
    while (1)
    {
        scanf("%s",ch); 
        if (ch[1]==‘t‘) break;
        int u=read(),v=read(),t,w,ans=-1;
        if (ch[1]==‘a‘) {t=lca(u,v); if (t!=v&&t!=u&&t!=1) ans=getmx(1,id[t],id[t]); ans=max(ans,max(solvemax(u,t),solvemax(v,t))); printf("%d\n",ans);}
        if (ch[1]==‘o‘) {w=read(); t=lca(u,v); solvechange(u,t,w); solvechange(v,t,w); if (t!=v&&t!=u&&t!=1) change(1,id[t],id[t],w);}
        if (ch[1]==‘d‘) {w=read(); t=lca(u,v); solveadd(u,t,w); solveadd(v,t,w); if (t!=v&&t!=u&&t!=1) add(1,id[t],id[t],w);} 
        if (ch[1]==‘h‘) {if (deep[e[u].v]<deep[e[u].u]) change(1,id[e[u].u],id[e[u].u],v); else change(1,id[e[u].v],id[e[u].v],v);}
    }
    return 0;
}