BZOJ 3786

传送门

用$\texttt{Splay}$维护$\texttt{DFS}$序

首先,每个节点到根路径的权值和即为$\texttt{DFS}$序的前缀和

然后对$\texttt{DFS}$序中每个节点存一下权值、进栈或出栈,拿这个建棵$\texttt{Splay}$,求前缀和时直接$\texttt{Splay}$到根然后求$\texttt{Sum}$

坑的地方在于对于一个点是进栈的点还是出栈的点的判断…这个有两种方法,一种是每个点存个布尔变量判断一下,还有就是存个$-1$或$1$的数与权值相乘 显然第二种比第一种不知道高到哪里去了

第一种方法需要进栈加出栈减,第二种方法只用直接加就行,结果拿第二种方法写的时候脑子抽了也搞成了进栈加出栈减…调了好久TAT

还有就是注意int64

卡时拿了PASCAL的一血2333


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program bzoj_3786;
var s:array[0..200002]of record fa,lc,rc,f,size,cnt,k,plus:longint; sum:int64; end;
seq,id:array[1..200002]of longint;
lst,w,pl,pr:array[0..100000]of longint;
l:array[1..100000]of record ed,pre:longint; end;
n,m,i,fa,a,b,tot,rt,len:longint;
c:char;
procedure link(a,b:longint);
begin
inc(tot);
l[tot].pre:=lst[a];
lst[a]:=tot;
l[tot].ed:=b;
end;
procedure dfs(t:longint);
var k:longint;
begin
inc(len);
seq[len]:=1;
id[len]:=t;
k:=lst[t];
while k<>0 do
begin
dfs(l[k].ed);
k:=l[k].pre;
end;
inc(len);
seq[len]:=-1;
id[len]:=t;
end;
procedure pushdown(t:longint);
var l,r:longint;
begin
l:=s[t].lc;
r:=s[t].rc;
if l<>0 then
begin
inc(s[l].plus,s[t].plus);
inc(s[l].sum,int64(s[t].plus)*int64(s[l].cnt));
inc(s[l].k,s[t].plus);
end;
if r<>0 then
begin
inc(s[r].plus,s[t].plus);
inc(s[r].sum,int64(s[t].plus)*int64(s[r].cnt));
inc(s[r].k,s[t].plus);
end;
s[t].plus:=0;
end;
procedure update(t:longint);
begin
if t=0 then exit;
if s[t].plus<>0 then pushdown(t);
s[t].size:=s[s[t].lc].size+s[s[t].rc].size+1;
s[t].cnt:=s[s[t].lc].cnt+s[s[t].rc].cnt+s[t].f;
s[t].sum:=s[s[t].lc].sum+s[s[t].rc].sum+s[t].f*s[t].k;
end;
procedure build(var t:longint;l,r,fa:longint);
var mid:longint;
begin
mid:=(l+r)>>1;
inc(tot);
t:=tot;
s[t].fa:=fa;
s[t].f:=seq[mid];
s[t].k:=w[id[mid]];
s[t].sum:=s[t].k;
s[t].size:=1;
s[t].cnt:=s[t].f;
if seq[mid]=1 then pl[id[mid]]:=tot;
if seq[mid]=-1 then pr[id[mid]]:=tot;
if l<mid then build(s[t].lc,l,mid-1,t);
if mid<r then build(s[t].rc,mid+1,r,t);
update(t);
end;
procedure l_rotate(t:longint);
var p:longint;
begin
p:=s[t].fa;
s[p].rc:=s[t].lc;
if s[t].lc<>0 then s[s[t].lc].fa:=p;
s[t].fa:=s[p].fa;
if p=s[s[p].fa].lc then s[s[p].fa].lc:=t;
if p=s[s[p].fa].rc then s[s[p].fa].rc:=t;
s[p].fa:=t;
s[t].lc:=p;
update(p);
update(t);
end;
procedure r_rotate(t:longint);
var p:longint;
begin
p:=s[t].fa;
s[p].lc:=s[t].rc;
if s[t].rc<>0 then s[s[t].rc].fa:=p;
s[t].fa:=s[p].fa;
if p=s[s[p].fa].lc then s[s[p].fa].lc:=t;
if p=s[s[p].fa].rc then s[s[p].fa].rc:=t;
s[p].fa:=t;
s[t].rc:=p;
update(p);
update(t);
end;
procedure splay(t:longint);
begin
while s[t].fa<>0 do
begin
if s[s[t].fa].plus<>0 then pushdown(s[t].fa);
if s[s[s[t].fa].lc].plus<>0 then pushdown(s[s[t].fa].lc);
if s[s[s[t].fa].rc].plus<>0 then pushdown(s[s[t].fa].rc);
if t=s[s[t].fa].lc then r_rotate(t) else l_rotate(t);
end;
rt:=t;
end;
function query(t:longint):int64;
begin
splay(t);
exit(s[s[t].lc].sum+s[t].f*s[t].k);
end;
function rank(t:longint):longint;
begin
splay(t);
exit(s[s[t].lc].size+1);
end;
function getk(t,k:longint):longint;
begin
if k=s[s[t].lc].size+1 then exit(t);
if k<=s[s[t].lc].size then exit(getk(s[t].lc,k))
else exit(getk(s[t].rc,k-s[s[t].lc].size-1));
end;
procedure move(x,y:longint);
var t,r1,r2:longint;
begin
r1:=rank(pl[x])-1;
r2:=rank(pr[x])+1;
splay(getk(rt,r1));
splay(getk(rt,r2));
t:=s[s[rt].lc].rc;
s[s[rt].lc].rc:=0;
update(s[rt].lc);
update(rt);
splay(getk(rt,rank(pr[y])-1));
splay(pr[y]);
s[s[rt].lc].rc:=t;
s[t].fa:=s[rt].lc;
update(s[rt].lc);
update(rt);
end;
procedure plus(t,d:longint);
var r1,r2:longint;
begin
r1:=rank(pl[t])-1;
r2:=rank(pr[t])+1;
splay(getk(rt,r1));
splay(getk(rt,r2));
t:=s[s[rt].lc].rc;
inc(s[t].sum,int64(d)*int64(s[t].cnt));
inc(s[t].plus,d);
inc(s[t].k,d);
update(s[rt].lc);
update(rt);
end;
begin
readln(n);
tot:=0;
for i:=2 to n do
begin
read(fa);
link(fa,i);
end;
for i:=1 to n do read(w[i]);
len:=1;
dfs(1);
inc(len);
tot:=0;
build(rt,1,len,0);
readln(m);
for i:=1 to m do
begin
read(c,a);
if c<>'Q' then read(b);
readln;
case c of
'Q':writeln(query(pl[a]));
'C':move(a,b);
'F':plus(a,b);
end;
end;
end.