BZOJ 1103

树状数组+DFS序

#include<cstdio>#include<algorithm>#include<cstring>#include<iostream>#define MAXN 500500#define lowbit(x) (x&(-x))using namespace std;int n,m;int c[2*MAXN];struct node{    int from, to, next;}edge[MAXN*2];int q[MAXN*2];int top,tot;inline int read(){    int x=0;char ch=getchar();    while(ch<'0'||ch>'9')ch=getchar();    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}    return x;}int head[MAXN*2],cnt;int l[MAXN*2],r[MAXN*2],fa[2*MAXN];void add(int x,int y){    edge[++cnt].from=x;    edge[cnt].to=y;    edge[cnt].next=head[x];    head[x]=cnt;}void dfs(int x){    q[++top]=x;    while(top)    {        int now=q[top],f=fa[top--];        if (!l[now])        {            l[now]=++tot;            q[++top]=now;            for (int i=head[now];i;i=edge[i].next)            {                if (edge[i].to==f) continue;                fa[++top]=now;                q[top]=edge[i].to;            }        }        else r[now]=++tot;    }    return ;}int query(int x){    int sum=0;    for (int i=x;i;i-=lowbit(i))    {        sum+=c[i];    }    return sum;}void update(int x,int delta){    for (int i=x;i<=2*n;i+=lowbit(i))    {        c[i]+=delta;    }    return ;}int main(){    n=read();    for (int i=1;i<n;i++)    {        int x,y;        x=read();y=read();        add(x,y);add(y,x);    }    dfs(1);    for (int i=1;i<=n;i++)    {        update(l[i],1);update(r[i],-1);    }     int mark=0;    m=read();    while (mark<m)    {        char ch[5];        scanf("%s",ch);        if (ch[0]=='A')        {            int x,y;            x=read(),y=read();            update(l[y],-1);            update(r[y],1);        }        else        {            int x;            x=read();            mark++;            printf("%d\n",query(l[x])-1);        }    }    return 0;}