Submission #576679

#	Time	Username	Problem	Language	Result	Execution time	Memory
576679		eecs	Through Another Maze Darkly (CCO21_day1problem3)	C++17	25 / 25	1176 ms	198916 KiB

Main

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

typedef long long ll;
const int maxn = 800010;
int n, m, tot, ver[maxn << 1], lev[maxn], id[maxn], ans[maxn];
ll q[maxn];
vector<int> G[maxn], V[maxn];

#define mid ((l + r) >> 1)
#define ls (k << 1)
#define rs (k << 1 | 1)
int sz[maxn << 3];

void upd(int k, int l, int r, int p) {
    sz[k]++;
    if (l < r) mid >= p ? upd(ls, l, mid, p) : upd(rs, mid + 1, r, p);
}

int get(int k, int l, int r, int p) {
    if (l == r) return ver[l];
    return sz[ls] >= p ? get(ls, l, mid, p) : get(rs, mid + 1, r, p - sz[ls]);
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0);
    cin >> n >> m;
    for (int i = 1, k; i <= n; i++) {
        cin >> k, G[i].resize(k);
        for (int &x : G[i]) cin >> x;
        rotate(G[i].begin(), G[i].begin() + 1, G[i].end());
    }
    auto dfs = [&](auto self, int u, int fa) -> void {
        if (u > 1) ver[++tot] = u, V[lev[u]].push_back(tot);
        bool flag = 0;
        for (int v : G[u]) {
            if (v == fa) { flag = 1; continue; }
            if (!flag) continue;
            lev[v] = lev[u] + 1, self(self, v, u);
            ver[++tot] = u, V[lev[v]].push_back(tot);
        }
        for (int v : G[u]) {
            if (v == fa) break;
            lev[v] = lev[u], self(self, v, u);
            ver[++tot] = u, V[lev[v]].push_back(tot);
        }
    };
    lev[1] = 1, dfs(dfs, 1, 0);
    for (int i = 1; i <= m; i++) {
        cin >> q[i];
    }
    iota(id + 1, id + m + 1, 1);
    sort(id + 1, id + m + 1, [&](int i, int j) { return q[i] < q[j]; });
    ll cur = 0;
    for (int i = 1, j = 1; i <= m; i++) {
        for (; j <= n && cur < q[id[i]]; j++) {
            for (int x : V[j]) upd(1, 1, tot, x);
            cur += sz[1];
        }
        ll x = q[id[i]] - (cur - sz[1]);
        ans[id[i]] = get(1, 1, tot, (x - 1) % (2 * n - 2) + 1);
    }
    for (int i = 1; i <= m; i++) {
        cout << ans[i] << "\n";
    }
    return 0;
}

• Subtask 1: 4 / 4
• Subtask 2: 4 / 4
• Subtask 3: 12 / 12
• Subtask 4: 5 / 5