Submission #883303

#	Time	Username	Problem	Language	Result	Execution time	Memory
883303		vjudge1	Ball Machine (BOI13_ballmachine)	C++17	100 / 100	187 ms	29216 KiB

ballmachine

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

const int N = 100'000;

int n, q, root;
int cntRank, rnk[N + 10], subMin[N + 10], revRank[N + 10];
int par[N + 10], h[N + 10], sz[N + 10];
int tim, st[N + 10], head[N + 10], revSt[N + 10];
vector<int> adj[N + 10];
vector<pair<int, int>> adj2[N + 10];

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

void init(int u = root) {
    h[u] = h[par[u]] + 1;
    sz[u] = 1;
    subMin[u] = u;
    for (auto v: adj[u]) {
        init(v);
        sz[u] += sz[v];
        subMin[u] = min(subMin[u], subMin[v]);
        adj2[u].push_back({subMin[v], v});
    }
    sort(adj2[u].begin(), adj2[u].end());
}

void calcRank(int u = root) {
    for (auto [x, v]: adj2[u])
        calcRank(v);
    rnk[u] = ++cntRank;
    revRank[cntRank] = u;
}

void hld(int u = root, int hed = 0) {
    head[u] = (hed? hed: u);
    st[u] = ++tim;
    revSt[tim] = u;
    int bigChild = 0;
    for (auto v: adj[u])
        if (sz[v] > sz[bigChild])
            bigChild = v;
    if (bigChild)
        hld(bigChild, head[u]);
    for (auto v: adj[u])
        if (v != bigChild)
            hld(v, 0);
}

int mn[2][4 * N + 10];

int get(int st, int en, int t, int id = 1, int l = 1, int r = n + 1) {
    if (en <= l || r <= st || mn[t][id])
        return 0;
    if (l + 1 == r)
        return l;
    int mid = (l + r) >> 1;
    int case1 = get(st, en, t, id << 1, l, mid);
    if (case1)
        return case1;
    return get(st, en, t, id << 1 | 1, mid, r);
}

void update(int idx, int val, int t, int id = 1, int l = 1, int r = n + 1) {
    if (idx < l || r <= idx)
        return;
    if (l + 1 == r) {
        mn[t][id] = val;
        return;
    }
    int mid = (l + r) >> 1;
    update(idx, val, t, id << 1, l, mid);
    update(idx, val, t, id << 1 | 1, mid, r);
    mn[t][id] = min(mn[t][id << 1], mn[t][id << 1 | 1]);
}

void build() {
    fill(mn[1] + 1, mn[1] + 4 * n + 10, 1);
}

int lastHave(int u) {
    int res = 0;
    while (u) {
        int tmp = get(st[head[u]], st[u] + 1, 1);
        if (tmp)
            res = tmp;
        u = par[head[u]];
    }
    return revSt[res];
}

void queryDel() {
    int u;
    cin >> u;
    int p = lastHave(u);
    cout << h[u] - h[p] << '\n';
    update(st[p], 1, 1);
    update(rnk[p], 0, 0);
}

void queryAdd() {
    int k;
    cin >> k;
    int ans;
    while (k--) {
        int u = revRank[get(1, n + 1, 0)];
        update(st[u], 0, 1);
        update(rnk[u], 1, 0);
        ans = u;
    }
    cout << ans << '\n';
}

void solve() {
    while (q--) {
        int type;
        cin >> type;
        if (type == 1)
            queryAdd();
        else
            queryDel();
    }
    cout.flush();
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    readInput();
    init();
    calcRank();
    hld();
    build();
    solve();
    return 0;
}

Compilation message (stderr)

ballmachine.cpp: In function 'void queryAdd()':
ballmachine.cpp:120:20: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  120 |     cout << ans << '\n';
      |                    ^~~~

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