#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 200010
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,cnt,cnt2,tt,lca,x,y,z;
struct edge{
int to,next,v,rnk;
}e[2*N];
struct segtree{
int l,r,mx,tag,cover;
}tree[4*N];
int query[N],v[N];
int head[N];
bool mrk[N];int depth[N],son[N],fa[N][21];
int place[N],pplace[N],belong[N];
char ch[100];
inline void ins(int u,int v,int w,int rnk)
{
e[++cnt].to=v;
e[cnt].v=w;
e[cnt].next=head[u];
e[cnt].rnk=rnk;
head[u]=cnt;
}
inline void insert(int u,int v,int w,int rnk)
{
ins(u,v,w,rnk);
ins(v,u,w,rnk);
}
inline void dfs1(int x,int dep)
{
if(mrk[x])return;
mrk[x]=1;depth[x]=dep;son[x]=1;
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;
query[e[i].rnk]=e[i].to;
v[e[i].to]=e[i].v;
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=20;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 pushdown(int k)
{
int l=tree[k].l,r=tree[k].r,tag=tree[k].tag,cov=tree[k].cover;
tree[k].tag=0;tree[k].cover=-1;
if (l==r)return;
if (cov!=-1)
{
tree[k<<1].mx=tree[k<<1|1].mx=cov;
tree[k<<1].tag=tree[k<<1|1].tag=0;
tree[k<<1].cover=tree[k<<1|1].cover=cov;
}
if (tag)
{
tree[k<<1].mx+=tag;
if (tree[k<<1].cover!=-1)tree[k<<1].cover+=tag;
else tree[k<<1].tag+=tag;
tree[k<<1|1].mx+=tag;
if (tree[k<<1|1].cover!=-1)tree[k<<1|1].cover+=tag;
else tree[k<<1|1].tag+=tag;
}
}
inline void update(int k)
{
tree[k].mx=max(tree[k<<1].mx,tree[k<<1|1].mx);
}
inline void buildtree(int now,int l,int r)
{
tree[now].l=l;tree[now].r=r;
tree[now].cover=-1;
if (l==r)
{
tree[now].mx=v[pplace[l]];
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)return tree[now].mx;
int mid=(l+r)>>1;
if (y<=mid)return ask_in_tree(now<<1,x,y);
else if(x>mid)return ask_in_tree(now<<1|1,x,y);
return max(ask_in_tree(now<<1,x,mid),ask_in_tree(now<<1|1,mid+1,y));
}
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].mx=dat;
tree[now].cover=dat;
tree[now].tag=0;
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 void add_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].tag+=dat;
tree[now].mx+=dat;
return;
}
int mid=(l+r)>>1;
if (y<=mid)add_in_tree(now<<1,x,y,dat);
else if (x>mid)add_in_tree(now<<1|1,x,y,dat);
else
{
add_in_tree(now<<1,x,mid,dat);
add_in_tree(now<<1|1,mid+1,y,dat);
}
update(now);
}
inline int ask(int from,int to)
{
int l,r,mx=0;
while (belong[from]!=belong[to])
{
l=place[belong[from]];
r=place[from];
mx=max(mx,ask_in_tree(1,l,r));
from=fa[belong[from]][0];
}
l=place[to]+1;r=place[from];
if (l>r)return mx;
mx=max(mx,ask_in_tree(1,l,r));
return mx;
}
inline void add(int from,int to,int dat)
{
int l,r;
while (belong[from]!=belong[to])
{
l=place[belong[from]];
r=place[from];
add_in_tree(1,l,r,dat);
from=fa[belong[from]][0];
}
l=place[to]+1;r=place[from];
if (l>r)return;
add_in_tree(1,l,r,dat);
}
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]+1;r=place[from];
if (l>r)return;
change_in_tree(1,l,r,dat);
}
int main()
{
n=read();
for (int i=1;i<n;i++)
{
x=read();
y=read();
z=read();
insert(x,y,z,++cnt2);
}
dfs1(1,1);
dfs2(1,1);
buildtree(1,1,n);
while (1)
{
scanf("%s",ch);
if(ch[1]==‘t‘)break;//stop
if (ch[1]==‘a‘)//max
{
x=read();y=read();
lca=LCA(x,y);
printf("%d\n",max(ask(x,lca),ask(y,lca)));
}
if (ch[1]==‘o‘)//cover
{
x=read();y=read();z=read();
lca=LCA(x,y);
change(x,lca,z);change(y,lca,z);
}
if (ch[1]==‘d‘)//add
{
x=read();y=read();z=read();
lca=LCA(x,y);
add(x,lca,z);add(y,lca,z);
}
if(ch[1]==‘h‘)//change
{
x=read();y=read();
change_in_tree(1,place[query[x]],place[query[x]],y);
}
}
return 0;
}
原文：http://www.cnblogs.com/zhber/p/4125675.html