2024广东省赛 C.DFS序

题目

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define fi first
#define se second
#define lson p << 1
#define rson p << 1 | 1
#define ll long long
const int maxn = 1e6 + 5, inf = 1e9, maxm = 4e4 + 5, base = 37;
const int N = 4e3;
const int mod = 1e9 + 7;
// const int mod = 998244353;
// const __int128 mod = 212370440130137957LL;

int n, m;
int a[maxn];

//long long ? maxn ? n? m?
void solve(){
    ll res = 0;
    cin >> n;
    vector<vector<int>> G(n + 1);
    vector<int> siz(n + 1), sum(n + 1);
    for(int i = 1; i <= n; i++){
        cin >> a[i];
    }
    for(int i = 2; i <= n; i++){
        int j;
        cin >> j;
        G[j].pb(i);
    }
    auto init = [&](auto self, int u) -> void {
        siz[u] = 1;
        sum[u] = a[u];