NC23051 华华和月月种树(DFS序+树状数组)

题目链接

题意：






题解：









AC代码

/*
    Author : zzugzx
    Lang : C++
    Blog : blog.csdn.net/qq_43756519
*/
#include<bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(), (x).end()
#define endl '\n'
#define SZ(x) (int)x.size()
#define mem(a, b) memset(a, b, sizeof(a))

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int mod = 1e9 + 7;
//const int mod = 998244353;

const double eps = 1e-6;
const double pi = acos(-1.0);
const int maxn = 1e6 + 10;
const int N = 1e2 + 5;
const ll inf = 0x3f3f3f3f;
const ll oo = 8e18;
const int dir[][2]={{0, 1}, {1, 0}, {0, -1}, {-1, 0}, {1, 1}, {1, -1}, {-1, 1}, {-1, -1}};
vector<int> g[maxn];
int cnt, l[maxn], r[maxn], c[maxn];
int lowbit(int x) {
    return x & (-x);
}
void add(int x, int v) {
    while (x <= cnt + 1)
        c[x] += v, x += lowbit(x);
}
int query(int x) {
    int res = 0;
    while (x)
        res += c[x], x -= lowbit(x);
    return res;
}
void dfs(int u) {
    l[u] = ++cnt;
    for (auto v : g[u]) {
        dfs(v);
    }
    r[u] = cnt;
}
int op[maxn], a[maxn], b[maxn], val[maxn];
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0); cout.tie(0);
//  freopen("in.txt", "r", stdin);
//  freopen("out.txt", "w", stdout);
    int m;
    cin >> m;
    for (int i = 1; i <= m; i++) {
        cin >> op[i] >> a[i];
        if (op[i] == 2) cin >> b[i];
        else if (op[i] == 1) {
            g[a[i]].pb(++cnt);
            b[i] = cnt;
        }
    }
    dfs(0);
    for (int i = 1; i <= m; i++) {
        if (op[i] == 1)
            val[l[b[i]]] -= query(l[a[i]]);
        else if (op[i] == 2) {
            add(l[a[i]], b[i]);
            add(r[a[i]] + 1, -b[i]);
        }
        else cout << val[l[a[i]]] + query(l[a[i]]) << endl;
    }
    return 0;
}