#include <bits/stdc++.h>
#define tt cin.tie(0), cout.tie(0), ios_base::sync_with_stdio(0)
#define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
#define ll long long
#define ull unsigned long long
#define i128 __int128
#define db long double
#define sz(a) ((int)(a).size())
#define pb emplace_back
#define pf emplace_front
#define pob pop_back
#define pof pop_front
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define ins emplace
#define mp make_pair
using namespace std;
const int MOD = 1e9+7, MAXN = 1e5+5;
const string NAME = "";
int n,q,par[MAXN],dist[MAXN],depth[MAXN];
int sz[MAXN],head[MAXN],pos[MAXN],curpos=0;
ll rs=0,edge[MAXN];
vector<pair<int,int>> adj[MAXN];
pair<pair<int,ll>,pair<int,ll>> dp[MAXN];
inline void maximize(pair<pair<int,ll>,pair<int,ll>>& p, pair<int,ll> x){
if(x.fi==p.fi.fi) p.fi.se=x.se;
else if(x.fi==p.se.fi) p.se.se=x.se;
else if(x.se>p.fi.se) swap(p.fi,p.se), p.fi=x;
else if(x.se>p.se.se) p.se=x;
}
void dfs(int u){
sz[u]=1;
for(pair<int,int>& e : adj[u]){
if(e.fi==par[u]) continue;
depth[e.fi]=depth[u]+1;
dfs(e.fi);
sz[u]+=sz[e.fi];
}
}
void HLD(int u, int curhead){
head[u]=curhead, pos[u]=++curpos;
int heavy=0;
for(pair<int,int>& e : adj[u])
if(e.fi!=par[u]&&sz[e.fi]>sz[heavy]) heavy=e.fi;
if(heavy!=0) HLD(heavy,curhead);
for(pair<int,int>& e : adj[u])
if(e.fi!=par[u]&&e.fi!=heavy) HLD(e.fi,e.fi);
for(pair<int,int>& e : adj[u])
if(e.fi!=par[u]) maximize(dp[pos[u]],{pos[e.fi],dp[pos[e.fi]].fi.se+e.se});
rs+=dp[pos[u]].fi.se+dp[pos[u]].se.se;
}
inline void update(int x, pair<int,ll> val){
while(x>0){
for(int i=pos[x], lim=pos[head[x]]; i>=lim; --i){
if(dp[i].se.se>val.se) return;
ll cur=rs;
pair<ll,ll> tmp = {dp[i].fi.se,dp[i].se.se};
rs-=dp[i].fi.se+dp[i].se.se;
maximize(dp[i],val);
rs+=dp[i].fi.se+dp[i].se.se;
if(val.se<dp[i].fi.se) return;
val.fi=i, val.se+=edge[i];
}
x=par[head[x]];
}
}
int main()
{
tt;
if(fopen((NAME + ".INP").c_str(), "r")) fo;
cin >> n;
for(int i = 2; i<=n; ++i)
cin >> par[i], ++par[i];
for(int i = 2; i<=n; ++i){
cin >> dist[i];
adj[i].pb(par[i],dist[i]), adj[par[i]].pb(i,dist[i]);
}
dfs(1);
HLD(1,1);
for(int i = 2; i<=n; ++i)
edge[pos[i]]=dist[i];
cout << rs << "\n";
cin >> q;
while(q--){
int x,y;
cin >> x >> y;
++x, edge[pos[x]]+=y;
if(dp[pos[x]].fi.se+edge[pos[x]]>=dp[pos[par[x]]].se.se) update(par[x],{pos[x],dp[pos[x]].fi.se+edge[pos[x]]});
cout << rs << "\n";
}
}
컴파일 시 표준 에러 (stderr) 메시지
arboras.cpp: In function 'int main()':
arboras.cpp:3:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arboras.cpp:72:45: note: in expansion of macro 'fo'
72 | if(fopen((NAME + ".INP").c_str(), "r")) fo;
| ^~
arboras.cpp:3:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arboras.cpp:72:45: note: in expansion of macro 'fo'
72 | if(fopen((NAME + ".INP").c_str(), "r")) fo;
| ^~
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