ZJOI2008 树的统计 树链剖分学习

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
#define LL long long
#define INF 0x3fffffff
#define FOR(i,x,y)  for(int i = x;i < y;i ++)
#define IFOR(i,x,y) for(int i = x;i > y;i --)
#define lrt rt<<1
#define rrt rt<<1|1
#define lson rt<<1,l,mid
#define rson rt<<1|1,mid+1,r
#define MAXN 33000

using namespace std;

int n,p;

struct Edge{
int u,v;
int nt;
}edge[MAXN<<1];

int head[MAXN],edge_cnt;

void add_edge(int u,int v){
edge[edge_cnt].u = u;
edge[edge_cnt].v = v;
edge[edge_cnt].nt = head[u];
head[u] = edge_cnt++;
}

int val0[MAXN];
int fa[MAXN],sz[MAXN],son[MAXN],dep[MAXN],top[MAXN],w[MAXN],val[MAXN];
int totw;

void dfs1(int u,int father,int depth){
fa[u] = father; dep[u] = depth; sz[u] = 1;
int idd = -1,maxx = -1;
for(int i = head[u];i != -1;i = edge[i].nt){
int v = edge[i].v;
if(v == father) continue;
dfs1(v,u,depth+1);
sz[u] += sz[v];
if(maxx < sz[v])    {maxx = sz[v];idd = v;}
}
son[u] = idd;
}

void dfs2(int u,int father){
if(son[u] == -1)    return;
top[son[u]] = top[u];
w[son[u]] = ++totw;
val[totw] = val0[son[u]];
dfs2(son[u],u);
for(int i = head[u];i != -1;i = edge[i].nt){
int v = edge[i].v;
if(v == father) continue;
if(v == son[u]) continue;
top[v] = v;
w[v] = ++totw;
val[totw] = val0[v];
dfs2(v,u);
}
}

struct Tree{
int l,r;
int maxx,sum;
}tree[MAXN<<2];

void PushUp(int rt){
tree[rt].maxx = max(tree[lrt].maxx,tree[rrt].maxx);
tree[rt].sum = tree[lrt].sum + tree[rrt].sum;
}

void Build(int rt,int l,int r){
tree[rt].l = l; tree[rt].r = r;
if(l == r){
tree[rt].maxx = tree[rt].sum = val[l];
return;
}
int mid = (l+r)>>1;
Build(lson);
Build(rson);
PushUp(rt);
}

void Modify(int rt,int x,int value){
if(tree[rt].l == tree[rt].r){
tree[rt].maxx = tree[rt].sum = value;
return;
}
int mid = (tree[rt].l + tree[rt].r)>>1;
if(x <= mid) Modify(lrt,x,value);
else Modify(rrt,x,value);
PushUp(rt);
}

int Q_Max(int rt,int l,int r){
if(tree[rt].l == l && tree[rt].r == r){
return tree[rt].maxx;
}
int mid = (tree[rt].l + tree[rt].r)>>1;
if(r <= mid) return Q_Max(lrt,l,r);
else if(l > mid) return Q_Max(rrt,l,r);
else{
return max(Q_Max(lson),Q_Max(rson));
}
}

int Q_Sum(int rt,int l,int r){
if(tree[rt].l == l && tree[rt].r == r){
return tree[rt].sum;
}
int mid = (tree[rt].l + tree[rt].r)>>1;
if(r <= mid) return Q_Sum(lrt,l,r);
else if(l > mid) return Q_Sum(rrt,l,r);
else{
return Q_Sum(lson)+Q_Sum(rson);
}
}

int Max(int l,int r){
int ans = -INF;
while(top[l] != top[r]){
if(dep[top[l]] >= dep[top[r]]){
ans = max(ans,Q_Max(1,w[top[l]],w[l]));
l = fa[top[l]];
}
else{
ans = max(ans,Q_Max(1,w[top[r]],w[r]));
r = fa[top[r]];
}
}
if(l == r)  ans = max(ans,Q_Max(1,w[l],w[r]));
else if(dep[l] >= dep[r]){
ans = max(ans,Q_Max(1,w[r],w[l]));
}
else ans = max(ans,Q_Max(1,w[l],w[r]));
return ans;
}

int Sum(int l,int r){
int ans = 0;
while(top[l] != top[r]){
if(dep[top[l]] >= dep[top[r]]){
ans += Q_Sum(1,w[top[l]],w[l]);
l = fa[top[l]];
}
else{
ans += Q_Sum(1,w[top[r]],w[r]);
r = fa[top[r]];
}
}
if(l == r)  ans += Q_Sum(1,w[l],w[r]);
else if(dep[l] >= dep[r]) ans += Q_Sum(1,w[r],w[l]);
else ans += Q_Sum(1,w[l],w[r]);
return ans;
}

int main()
{
//freopen("test.in","r",stdin);
while(~scanf("%d",&n)){
edge_cnt = 0;
memset(head,-1,sizeof(head));
FOR(i,1,n){
int u,v;
scanf("%d%d",&u,&v);
add_edge(u,v);
add_edge(v,u);
}
FOR(i,1,n+1)    scanf("%d",&val0[i]);
dfs1(1,-1,1);
totw = 0;
top[1] = 1;
val[1] = val0[1];
w[1] = ++totw;
dfs2(1,-1);
Build(1,1,totw);
scanf("%d",&p);
char op[10];
while(p--){
scanf("%s",op);
if(!strcmp(op,"CHANGE")){
int u,t;
scanf("%d%d",&u,&t);
Modify(1,w[u],t);
}
else if(!strcmp(op,"QMAX")){
int l,r;
scanf("%d%d",&l,&r);
printf("%d\n",Max(l,r));
}
else{
int l,r;
scanf("%d%d",&l,&r);
printf("%d\n",Sum(l,r));
}
}
}
return 0;
}