安装就把根节点到它全设为 1
删除就把以它为根的子树全设为 0
记得标记初始化为-1，因为标记是 0 的情况也是要处理的。
#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
int n, m, uu, hea[100005], cnt, dep[100005], fa[100005], son[100005], siz[100005];
int top[100005], idx[100005], qwq;
char ss[15];
struct Edge{
int too, nxt;
}edge[200005];
struct SGT{
int sum[400005], tag[400005];
void build(int o, int l, int r){
tag[o] = -1;
if(l==r) sum[o] = 0;
else{
int mid=(l+r)>>1;
int lson=o<<1;
int rson=lson|1;
if(l<=mid) build(lson, l, mid);
if(mid<r) build(rson, mid+1, r);
sum[o] = sum[lson] + sum[rson];
}
}
void pushDown(int o, int l, int r, int lson, int rson, int mid){
tag[lson] = tag[o];
tag[rson] = tag[o];
sum[lson] = (mid-l+1) * tag[o];
sum[rson] = (r-mid) * tag[o];
tag[o] = -1;
}
void update(int o, int l, int r, int x, int y, int k){
if(l>=x && r<=y){
sum[o] = (r-l+1) * k;
tag[o] = k;
}
else{
int mid=(l+r)>>1;
int lson=o<<1;
int rson=lson|1;
if(tag[o]!=-1) pushDown(o, l, r, lson, rson, mid);
if(x<=mid) update(lson, l, mid, x, y, k);
if(mid<y) update(rson, mid+1, r, x, y, k);
sum[o] = sum[lson] + sum[rson];
}
}
}sgt;
void add_edge(int fro, int too){
edge[++cnt].nxt = hea[fro];
edge[cnt].too = too;
hea[fro] = cnt;
}
void dfs1(int x, int f){
dep[x] = dep[f] + 1;
fa[x] = f;
siz[x] = 1;
int maxSon=-1;
for(int i=hea[x]; i; i=edge[i].nxt){
int t=edge[i].too;
if(t!=f){
dfs1(t, x);
siz[x] += siz[t];
if(siz[t]>maxSon) maxSon = siz[t], son[x] = t;
}
}
}
void dfs2(int x, int topf){
top[x] = topf;
idx[x] = ++qwq;
if(!son[x]) return ;
dfs2(son[x], topf);
for(int i=hea[x]; i; i=edge[i].nxt){
int t=edge[i].too;
if(t!=fa[x] && t!=son[x])
dfs2(t, t);
}
}
void upd(int xx, int yy){
while(top[xx]!=top[yy]){
if(dep[top[xx]]<dep[top[yy]]) swap(xx, yy);
sgt.update(1, 1, n, idx[top[xx]], idx[xx], 1);
xx = fa[top[xx]];
}
if(dep[xx]>dep[yy]) swap(xx, yy);
sgt.update(1, 1, n, idx[xx], idx[yy], 1);
}
int main(){
cin>>n;
for(int i=2; i<=n; i++){
scanf("%d", &uu);
add_edge(i, uu+1);
add_edge(uu+1, i);
}
dfs1(1, 0);
dfs2(1, 1);
sgt.build(1, 1, n);
cin>>m;
while(m--){
scanf("%s %d", ss, &uu);
uu++;
if(ss[0]==‘i‘){
int tmp=sgt.sum[1];
upd(1, uu);
printf("%d\n", sgt.sum[1]-tmp);
}
else{
int tmp=sgt.sum[1];
sgt.update(1, 1, n, idx[uu], idx[uu]+siz[uu]-1, 0);
printf("%d\n", tmp-sgt.sum[1]);
}
}
return 0;
}