Submission #1075688

#	Time	Username	Problem	Language	Result	Execution time	Memory
1075688		ShadowShark	Ball Machine (BOI13_ballmachine)	C++17	68.42 / 100	84 ms	22864 KiB

ballmachine

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

const int maxN = 1e5 + 5;
vector<int> adj[maxN];
int mn[maxN], depth[maxN], order[maxN], save[maxN], par[17][maxN];
int tick = 0, timeDfs = 0;
bool added[maxN];

void dfs(int u) {
    mn[u] = u;

    for (auto v: adj[u]) {
        par[0][v] = u;
        depth[v] = depth[u] + 1;
        dfs(v);
        mn[u] = min(mn[u], mn[v]);
    }
}

void dfs_order(int u) {
    for (auto v: adj[u]) {
        dfs_order(v);
    }

    order[++tick] = u;
}

bool cmp (int u, int v) {
    return mn[u] < mn[v];
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int n, q, root = 0;
    cin >> n >> q;

    for (int i = 1; i <= n; i++) {
        int x;
        cin >> x;

        if (x == 0) root = i;
            else adj[x].push_back(i);
    }

    depth[root] = 1;
    dfs(root);
    for (int i = 1; i <= n; i++)
        if (adj[i].size() > 0) sort(adj[i].begin(), adj[i].end(), cmp);

    dfs_order(root);

    stack<int> pq;

    for (int i = n; i >= 1; i--)
        pq.push(i);

    for (int i = 1; i <= n; i++)
        save[order[i]] = i;

    for (int k = 1; k <= 16; k++) {
        for (int i = 1; i <= n; i++)
            par[k][i] = par[k - 1][par[k - 1][i]];
    }

    while (q--) {
        int type;
        cin >> type;

        if (type == 1) {
            int k;
            cin >> k;

            int ans = 0;
            while (k--) {
                int ord = pq.top(), u = order[ord];
                pq.pop();
                added[u] = true;
                ans = u;
            }
            cout << ans << '\n';
        }
        else {
            int u; cin >> u; int ans = u;
            for (int k = 16; k >= 0; k--) {
                if (par[k][ans] == 0) continue;
                int v = par[k][ans];
                if (added[v]) ans = v;
            }
            cout << depth[u] - depth[ans] << '\n';
            pq.push(save[ans]);
            added[ans] = false;
        }
    }

    return 0;
}

• Subtask 1: 9.615384615384615 / 25
• Subtask 2: 17.142857142857142 / 30
• Subtask 3: 40 / 40
• Subtask 4: 1.6666666666666667 / 5