POJ 3237 Tree (树链剖分)

#include <iostream>
#include <string.h>
#include <math.h>
#include <queue>
#include <algorithm>
#include <stdlib.h>
#include <map>
#include <set>
#include <stdio.h>
using namespace std;
#define LL long long
#define pi acos(-1.0)
#pragma comment(linker, "/STACK:1024000000,1024000000")
const int mod=1e9+7;
const int INF=0x3f3f3f3f;
const double eqs=1e-3;
const int MAXN=10000+10;
#define root 1, tot, 1
#define lson l, mid, rt<<1
#define rson mid+1, r, rt<<1|1
int head[MAXN], cnt, tot;
int siz[MAXN], w[MAXN], top[MAXN], son[MAXN], dep[MAXN], fa[MAXN];
int Max[MAXN<<2], Min[MAXN<<2], lazy[MAXN<<2];
struct node
{
int u, v, w, next;
}edge[MAXN<<1];
void add(int u, int v, int w)
{
edge[cnt].u=u;
edge[cnt].v=v;
edge[cnt].w=w;
edge[cnt].next=head[u];
head[u]=cnt++;
}
void init()
{
memset(head,-1,sizeof(head));
cnt=tot=0;
memset(son,0,sizeof(son));
memset(dep,0,sizeof(dep));
memset(lazy,0,sizeof(lazy));
memset(Max,-INF,sizeof(Max));
memset(Min,INF,sizeof(Min));
}
void dfs1(int u, int p)
{
siz[u]=1;
for(int i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(v==p) continue ;
dep[v]=dep[u]+1;
fa[v]=u;
dfs1(v,u);
if(siz[son[u]]<siz[v]) son[u]=v;
}
}
void dfs2(int u, int tp)
{
w[u]=++tot;
top[u]=tp;
if(son[u]) dfs2(son[u],tp);
for(int i=head[u];i!=-1;i=edge[i].next){
int v=edge[i].v;
if(v!=fa[u]&&v!=son[u])
dfs2(v,v);
}
}
struct Line_Tree
{
void UpdateNode(int rt)
{
swap(Max[rt],Min[rt]);
Max[rt]*=-1;
Min[rt]*=-1;
}
void PushUp(int rt)
{
Max[rt]=max(Max[rt<<1],Max[rt<<1|1]);
Min[rt]=min(Min[rt<<1],Min[rt<<1|1]);
}
void PushDown(int rt)
{
if(lazy[rt]){
lazy[rt<<1]=1-lazy[rt<<1];
lazy[rt<<1|1]=1-lazy[rt<<1|1];
UpdateNode(rt<<1);
UpdateNode(rt<<1|1);
lazy[rt]=0;
}
}
void Update(int p, int x, int l, int r, int rt)
{
if(l==r){
Max[rt]=Min[rt]=x;
return ;
}
int mid=l+r>>1;
PushDown(rt);
if(p<=mid) Update(p,x,lson);
else Update(p,x,rson);
PushUp(rt);
}
void Negate(int ll, int rr, int l, int r, int rt)
{
if(ll<=l&&rr>=r){
lazy[rt]=1-lazy[rt];
UpdateNode(rt);
return ;
}
int mid=l+r>>1;
PushDown(rt);
if(ll<=mid) Negate(ll,rr,lson);
if(rr>mid) Negate(ll,rr,rson);
PushUp(rt);
}
int Query(int ll, int rr, int l, int r, int rt)
{
if(ll<=l&&rr>=r){
return Max[rt];
}
int mid=l+r>>1, ans=-INF;
PushDown(rt);
if(ll<=mid) ans=max(ans,Query(ll,rr,lson));
if(rr>mid) ans=max(ans,Query(ll,rr,rson));
return ans;
}
}lt;
void change(int u, int v)
{
int f1=top[u], f2=top[v];
while(f1!=f2){
if(dep[f1]<dep[f2]){
swap(u,v);
swap(f1,f2);
}
lt.Negate(w[f1],w[u],root);
u=fa[f1];f1=top[u];
}
if(u==v) return ;
if(dep[u]<dep[v]) swap(u,v);
lt.Negate(w[son[v]],w[u],root);
}
int solve(int u, int v)
{
int f1=top[u], f2=top[v], ans=-INF;
while(f1!=f2){
if(dep[f1]<dep[f2]){
swap(u,v);
swap(f1,f2);
}
ans=max(ans,lt.Query(w[f1],w[u],root));
u=fa[f1];f1=top[u];
}
if(u==v) return ans;
if(dep[u]<dep[v]) swap(u,v);
return max(ans,lt.Query(w[son[v]],w[u],root));
}
int main()
{
int T, n, i, u, v, c, id;
char s[10];
scanf("%d",&T);
while(T--){
scanf("%d",&n);
init();
for(i=1;i<n;i++){
scanf("%d%d%d",&u,&v,&c);
add(u,v,c);
add(v,u,c);
}
dfs1(1,-1);
dfs2(1,1);
for(i=0;i<cnt;i+=2){
u=edge[i].u;
v=edge[i].v;
if(dep[u]<dep[v]) swap(u,v);
lt.Update(w[u],edge[i].w,root);
}
while(scanf("%s",s)!=EOF&&s[0]!='D'){
if(s[0]=='C'){
scanf("%d%d",&id,&c);
u=edge[id-1<<1].u;
v=edge[id-1<<1].v;
if(dep[u]<dep[v]) swap(u,v);
lt.Update(w[u],c,root);
}
else if(s[0]=='N'){
scanf("%d%d",&u,&v);
change(u,v);
}
else{
scanf("%d%d",&u,&v);
printf("%d\n",solve(u,v));
}
}
}
return 0;
}