Submission #1091348

#	Time	Username	Problem	Language	Result	Execution time	Memory
1091348		ShadowShark	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	115 ms	22980 KiB

ballmachine

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

const int maxN = 1e5 + 5;
int a[maxN], mn[maxN], depth[maxN], par[20][maxN], order[maxN], cntOrder = 0;
bool picked[maxN];
vector<int> adj[maxN];

void pre_dfs(int u, int pre) {
    mn[u] = u;
    for (auto v: adj[u]) {
        if (v == pre) continue;
        depth[v] = depth[u] + 1;
        pre_dfs(v, u);
        mn[u] = min(mn[u], mn[v]);
    }
}

void dfs_order(int u, int pre) {
    for (auto v: adj[u]) {
        if (v == pre) continue;
        dfs_order(v, u);
    }
    order[u] = ++cntOrder;
}

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 = -1;
    cin >> n >> q;

    //for (int i = 1; i <= n; i++)
        //cin >> a[i];

    for (int i = 1; i <= n; i++) {
        cin >> par[0][i];
        if (par[0][i] == 0) root = i;
            else adj[par[0][i]].push_back(i);
    }

    pre_dfs(root, root);

    for (int i = 1; i <= n; i++)
        sort(adj[i].begin(), adj[i].end(), cmp);
    dfs_order(root, root);

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

    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    for (int i = 1; i <= n; i++)
        pq.push({order[i], i});

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

        if (type == 1) {
            int last;
            while (x--) {
                last = pq.top().second; pq.pop();
                picked[last] = true;
            }
            cout << last << '\n';
        }
        else {
            int u = x;
            for (int k = 16; k >= 0; k--) {
                int v = par[k][u];
                if (picked[v]) u = v;
            }
            cout << depth[x] - depth[u] << '\n';
            picked[u] = false;
            pq.push({order[u], u});
        }
    }

    return 0;
}

Compilation message (stderr)

ballmachine.cpp: In function 'int main()':
ballmachine.cpp:70:29: warning: 'last' may be used uninitialized in this function [-Wmaybe-uninitialized]
   70 |             cout << last << '\n';
      |                             ^~~~

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