poj 2763 Housewife Wind 树链剖分+LCA

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<vector>
#define maxn 100005
using namespace std;
int top[maxn],fa[maxn],son[maxn],size[maxn],id[maxn],num,dep[maxn],tot;
struct pppi{
int to;
int next;
}pp2[2*maxn];
int head[maxn];
vector<int >g[maxn];
void add(int u,int v){
pp2[tot].to=v;
pp2[tot].next=head[u];
head[u]=tot++;
pp2[tot].to=u;
pp2[tot].next=head[v];
head[v]=tot++;
}
struct ppi{
int from;
int to;
int cost;
}pp1[maxn];
struct pi{
int le,ri;
int sum;
}pp[4*maxn];
void build(int tot,int l,int r){
pp[tot].sum=0;
pp[tot].le=l;
pp[tot].ri=r;
if(l==r) return ;
build(2*tot,l,(l+r)/2);
build(2*tot+1,(l+r)/2+1,r);
}
void merg(int tot,int l,int k){
if(pp[tot].ri==pp[tot].le){
pp[tot].sum=k;
return ;
}
int mid;
mid=(pp[tot].le+pp[tot].ri)/2;
if(l<=mid) merg(2*tot,l,k);
else merg(2*tot+1,l,k);
pp[tot].sum=pp[2*tot].sum+pp[2*tot+1].sum;
}
int query(int tot,int l,int r){
if(pp[tot].le>=l&&pp[tot].ri<=r){
return pp[tot].sum;
}
int s=0;
int mid=(pp[tot].le+pp[tot].ri)/2;
if(l<=mid) s+=query(2*tot,l,r);
if(r>mid) s+=query(2*tot+1,l,r);
return s;
}
void dfs1(int u,int pa,int d){
dep[u]=d;
size[u]=1;
son[u]=0;
fa[u]=pa;
int k,v;
k=head[u];
while(k!=-1){
v=pp2[k].to;
if(v==pa){
k=pp2[k].next;
continue;
}
dfs1(v,u,d+1);
size[u]+=size[v];
if(size[son[u]]<size[v]) son[u]=v;
k=pp2[k].next;
}
}
void dfs2(int u,int pa,int tp){
int k,v;
id[u]=num++;
top[u]=tp;
if(son[u]) dfs2(son[u],u,tp);
k=head[u];
while(k!=-1){
v=pp2[k].to;
if(v==pa||v==son[u]){
k=pp2[k].next;
continue;
}
dfs2(v,u,v);
k=pp2[k].next;
}
}
int get(int u,int v){
int s=0,to1,to2;
to1=top[u];
to2=top[v];
while(to1!=to2){
if(dep[to1]<dep[to2]){
swap(to1,to2);
swap(u,v);
}
s+=query(1,id[to1],id[u]);
u=fa[to1];
to1=top[u];
}
if(u==v) return s;
if(dep[u]>dep[v]) swap(u,v);
s+=query(1,id[u]+1,id[v]);
return s;
}
int main()
{
int i,n,m,p,k,s;
scanf("%d%d%d",&n,&m,&s);
build(1,1,n-1);
memset(head,-1,sizeof(head));
tot=0;
for(i=1;i<=n-1;i++){
scanf("%d%d%d",&pp1[i].from,&pp1[i].to,&pp1[i].cost);
add(pp1[i].from,pp1[i].to);
}
num=0;
dfs1(1,1,1);
dfs2(1,1,1);
for(i=1;i<n;i++){
if(fa[pp1[i].from]==pp1[i].to){
merg(1,id[pp1[i].from],pp1[i].cost);
}
else merg(1,id[pp1[i].to],pp1[i].cost);
}
for(i=0;i<m;i++){
scanf("%d",&p);
if(p==0){
scanf("%d",&k);
printf("%d\n",get(s,k));
s=k;
}
else{
scanf("%d%d",&p,&k);
if(fa[pp1[p].from]==pp1[p].to) merg(1,id[pp1[p].from],k);
else  merg(1,id[pp1[p].to],k);
}
}
}