2017-09-28 15:55:47

【POI补全计划#43 POI2007 MEG】

1.树上单条边权-1

2.查询树上点到根路径上权值和

P.S.单点修改链上查询一般可以转化为dfs序，而且dfs序常数一般比树链剖分小（楼下的解法）

#include<iostream>
#include<cstdio>
#include<map>
using namespace std;
const int MAXN=250010;
struct node
{
int l,r,sum;
node *lson,*rson;
}*root,pool[MAXN*4];
int top;
node* build(int l,int r)
{
node *tmp=&pool[++top];
tmp->l=l;tmp->r=r;
tmp->sum=r-l+1;
if(l!=r)
{
int mid=(l+r)/2;
tmp->lson=build(l,mid);
tmp->rson=build(mid+1,r);
}
return tmp;
}
void change(node *cur,int pos)//minus 1
{
cur->sum--;
if(cur->l==cur->r)return;
if(cur->lson->r>=pos)change(cur->lson,pos);
else change(cur->rson,pos);
}
int query(node *cur,int l,int r)
{
if(cur->l==l&&cur->r==r)
return cur->sum;
if(cur->lson->r>=r)return query(cur->lson,l,r);
else if(cur->rson->l<=l)return query(cur->rson,l,r);
else return query(cur->lson,l,cur->lson->r)+query(cur->rson,cur->rson->l,r);
}
struct edge
{
int v,id;
edge *next;
}*h[MAXN],epool[MAXN*2];
int etop;
{
edge *tmp=&epool[++etop];tmp->v=v;tmp->next=h[u];h[u]=tmp;
edge *pmt=&epool[++etop];pmt->v=u;pmt->next=h[v];h[v]=pmt;
}
int dep[MAXN],siz[MAXN],pa[MAXN],maxson[MAXN],paedge[MAXN],pathroot[MAXN];
void dfs1(int u)
{
siz[u]=1;
for(edge *tmp=h[u];tmp;tmp=tmp->next)
{
if(!dep[tmp->v])
{
dep[tmp->v]=dep[u]+1;
pa[tmp->v]=u;
dfs1(tmp->v);
siz[u]+=siz[tmp->v];
if(siz[tmp->v]>siz[maxson[u]])maxson[u]=tmp->v;
}
}
}
int cur;
void dfs2(int u)
{
if(maxson[u])
{
paedge[maxson[u]]=++cur;
pathroot[maxson[u]]=pathroot[u];
dfs2(maxson[u]);
}
for(edge *tmp=h[u];tmp;tmp=tmp->next)
{
if(tmp->v!=maxson[u]&&dep[tmp->v]==dep[u]+1)
{
paedge[tmp->v]=++cur;
pathroot[tmp->v]=tmp->v;
dfs2(tmp->v);
}
}
}
inline int qtree(int x)
{
int ans=0;
while(x)
{
ans+=query(root,paedge[pathroot[x]],paedge[x]);
x=pa[pathroot[x]];
}
return ans;
}
int main()
{
int n,q,a,b;
char ch;
scanf("%d",&n);
for(int i=1;i<=n-1;i++)
{
scanf("%d%d",&a,&b);
}
dep[1]=1;
dfs1(1);
pathroot[1]=1;
dfs2(1);
root=build(0,n-1);
scanf("%d",&q);
for(int i=1;i<=n+q-1;i++)
{
scanf(" %c",&ch);
if(ch=='W')
{
scanf("%d",&a);
printf("%d\n",qtree(a)-1);
}
else
{
scanf("%d%d",&a,&b);
change(root,paedge[b]);
}
}
return 0;
}
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