bzoj P1036 [ZJOI2008]树的统计Count

传送门

嗯，一道裸裸的树剖。

代码：

#include<iostream>#include<stdio.h>using namespace std;const int Maxn=30005;const int oo=2147483647;struct segment{int v,next;}e[Maxn*2];struct Qtree{int l,r,mx,sum;}t[Maxn*4];int size[Maxn],pos[Maxn],head[Maxn],fa[Maxn],depth[Maxn],w[Maxn],top[Maxn];int cnt,tmp,n,q;void insert(int u,int v){    e[++cnt].v=v;e[cnt].next=head[u];head[u]=cnt;    e[++cnt].v=u;e[cnt].next=head[v];head[v]=cnt;}void dfs1(int x){size[x]=1;for(int i=head[x];i;i=e[i].next){if(e[i].v==fa[x])continue;depth[e[i].v]=depth[x]+1;fa[e[i].v]=x;dfs1(e[i].v);size[x]+=size[e[i].v];}}void dfs2(int x,int tp){int k=0;pos[x]=++tmp;;top[x]=tp;for(int i=head[x];i;i=e[i].next)if(depth[e[i].v]>depth[x]&&size[e[i].v]>size[k])k=e[i].v;if(k==0)return ;dfs2(k,tp);for(int i=head[x];i;i=e[i].next)if(depth[e[i].v]>depth[x]&&e[i].v!=k)dfs2(e[i].v,e[i].v);}void build(int l,int r,int rt){t[rt].l=l;t[rt].r=r;if(l==r)return ;int mid=(l+r)>>1;build(l,mid,rt<<1);build(mid+1,r,rt<<1|1);}int Qsum(int lf,int rf,int rt){int l=t[rt].l,r=t[rt].r,mid=(l+r)>>1,sum=0;if(l>=lf&&r<=rf)return t[rt].sum;if(lf<=mid)sum+=Qsum(lf,rf,rt<<1);      if(rf>mid)sum+=Qsum(lf,rf,rt<<1|1);      //t[rt].sum=t[rt<<1].sum+t[rt<<1|1].sum;      return sum;}int Qmax(int lf,int rf,int rt){int l=t[rt].l,r=t[rt].r,mid=(l+r)>>1,maxp=-oo;if(l>=lf&&r<=rf)return t[rt].mx;if(lf<=mid)maxp=max(maxp,Qmax(lf,rf,rt<<1));if(rf>mid)maxp=max(maxp,Qmax(lf,rf,rt<<1|1));//t[rt].mx=max(t[rt<<1].mx,t[rt<<1|1].mx);return maxp;}void change(int x,int d,int rt){    int l=t[rt].l,r=t[rt].r,mid=(l+r)>>1;    if(l==r){t[rt].sum=t[rt].mx=d;return;}    if(x<=mid)change(x,d,rt<<1);    else change(x,d,rt<<1|1);    t[rt].sum=t[rt<<1].sum+t[rt<<1|1].sum;    t[rt].mx=max(t[rt<<1].mx,t[rt<<1|1].mx);}int solvesum(int lf,int rf){int sum=0;while(top[lf]!=top[rf]){if(depth[top[lf]]<depth[top[rf]])swap(lf,rf);sum+=Qsum(pos[top[lf]],pos[lf],1);lf=fa[top[lf]];}if(pos[lf]>pos[rf])swap(lf,rf);sum+=Qsum(pos[lf],pos[rf],1);    return sum;}int solvemax(int lf,int rf){int maxp=-oo;while(top[lf]!=top[rf]){if(depth[top[lf]]<depth[top[rf]])swap(lf,rf);maxp=max(maxp,Qmax(pos[top[lf]],pos[lf],1));lf=fa[top[lf]];}if(pos[lf]>pos[rf])swap(lf,rf);maxp=max(maxp,Qmax(pos[lf],pos[rf],1));    return maxp;}int main(){    scanf("%d",&n);    for(int i=1;i<n;i++)    {int x,y;scanf("%d%d",&x,&y);insert(x,y);}    for(int i=1;i<=n;i++)scanf("%d",&w[i]);dfs1(1);dfs2(1,1);build(1,n,1);char ch[10];for(int i=1;i<=n;i++)        change(pos[i],w[i],1);    scanf("%d",&q);    for(int i=1;i<=q;i++)     {        int x,y;scanf("%s%d%d",ch,&x,&y);        if(ch[0]=='C'){w[x]=y;change(pos[x],y,1);}        else        {            if(ch[1]=='M')               printf("%d\n",solvemax(x,y));            else                printf("%d\n",solvesum(x,y));        }    }return 0;}