Submission #872042

#	Time	Username	Problem	Language	Result	Execution time	Memory
872042		vjudge1	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	161 ms	30156 KiB

ballmachine

#include <bits/stdc++.h>
using namespace std;

const int N = 100'000 + 7, L = 20 + 7;
vector<int> ord, adj[N];
int n, q, r, mn[N], idx[N], sp[L][N];
bool mark[N];
set<int> s;

void read_input() {
    cin >> n >> q;
    for (int i = 1; i <= n; i++) {
        int p;
        cin >> p;
        if (p == 0) {
            r = i;
        } else {
            adj[i].push_back(p);
            adj[p].push_back(i);
        }
    }
}

void dfs1(int v, int p) {
    mn[v] = v;
    for (int u : adj[v])
        if (u != p) {
            dfs1(u, v);
            mn[v] = min(mn[v], mn[u]);
        }
}

void dfs2(int v, int p) {
    sort(adj[v].begin(), adj[v].end(), [](int v1, int v2) -> bool { return mn[v1] < mn[v2]; });
    for (int u : adj[v])
        if (u != p)
            dfs2(u, v);
    ord.push_back(v);
}

void dfs3(int v, int p) {
    sp[0][v] = p;
    for (int i = 1; i < L; i++) {
        if (sp[i - 1][sp[i - 1][v]] == 0)
            break;
        else
            sp[i][v] = sp[i - 1][sp[i - 1][v]];
    }

    for (int u : adj[v])
        if (u != p)
            dfs3(u, v);
}

void pre_process() {
    dfs1(r, 0);
    ord.push_back(-1);
    dfs2(r, 0);
    dfs3(r, 0);
    for (int i = 1; i <= n; i++)
        idx[ord[i]] = i;
    for (int i = 1; i <= n; i++)
        s.insert(i);
}

void add(int x) {
    for (int i = 1; i <= x; i++) {
        int t = *s.begin();
        s.erase(t);
        mark[t] = true;
        
        if (i == x)
            cout << ord[t] << '\n';
    }
}

void remove(int v) {
    int res = 0, u = v;
    for (int i = L - 1; i >= 0; i--)
        if (mark[idx[sp[i][u]]]) {
            u = sp[i][u];
            res |= (1 << i);
        }

    mark[idx[u]] = false;
    s.insert(idx[u]);

    cout << res << '\n';
}

void solve() {
    while (q--) {
        int t, x;
        cin >> t >> x;
        if (t == 1)
            add(x);
        else
            remove(x);
    }
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    read_input();
    pre_process();
    solve();
}

• Subtask 1: 25 / 25
• Subtask 2: 30 / 30
• Subtask 3: 40 / 40
• Subtask 4: 5 / 5