Submission #646851

#	Time	Username	Problem	Language	Result	Execution time	Memory
646851		chenwz	Abracadabra (CEOI22_abracadabra)	C++11	100 / 100	608 ms	34240 KiB

Main

#include <bits/stdc++.h>
#define sz(v) ((int)(v).size())
using namespace std;
typedef long long lint;
typedef pair<int, int> pi;
using VI = vector<int>;
const int NN = 2e5 + 4;
struct BIT {
  int C[NN];
  void add(int x, int v) {
    while (x < NN) C[x] += v, x += x & -x;
  }
  int sum(int x) {
    int ret = 0;
    while (x) ret += C[x], x -= x & -x;
    return ret;
  }
  int kth(int x) {
    int pos = 0;
    for (int i = 17; i >= 0; i--)
      if (pos + (1 << i) < NN && C[pos + (1 << i)] < x)
        pos += (1 << i), x -= C[pos];
    return pos + 1;
  }
};
BIT S;
int main() {
  ios::sync_with_stdio(false), cin.tie(0);
  int n, q;
  cin >> n >> q;
  VI a(n), rev(n + 1), ans(q);
  vector<vector<pi>> v(n + 1);
  for (int i = 0; i < n; i++) cin >> a[i], rev[a[i]] = i;
  for (int i = 0, t, x; i < q; i++) {
    cin >> t >> x, t = min(t, n);
    if (t == 0)
      ans[i] = a[x - 1];
    else
      v[t].emplace_back(x - 1, i);
  }

  VI nxt(n), ds(n + 1);
  auto SetVal = [&](int x, int v) { S.add(x, v - ds[x]), ds[x] = v; };
  for (int i = 0; i < n;) {
    int j = i + 1;
    while (j < n && a[j] < a[i]) j++;
    SetVal(a[i], j - i), i = j;
  }
  VI v2;
  for (int i = n - 1; i >= 0; i--) {
    while (!v2.empty() && a[v2.back()] < a[i]) v2.pop_back();
    if (!v2.empty())
      nxt[i] = v2.back();
    else
      nxt[i] = n;
    v2.push_back(i);
  }

  for (int i = 1; i <= n; i++) {
    int itf = S.kth(n / 2 + 1), its = ds[itf], sum = S.sum(itf - 1);
    if (sum < n / 2) {
      int l = rev[itf], r = l + its;
      SetVal(a[l], n / 2 - sum);
      l += n / 2 - sum;
      for (int i = l; i < r; i = nxt[i]) SetVal(a[i], min(r, nxt[i]) - i);
    }
    for (auto p : v[i]) {
      int pos = p.first, idx = p.second, qos = S.kth(pos + 1),
          sum = S.sum(qos - 1);
      ans[idx] = a[rev[qos] + pos - sum];
    }
  }
  for (int x : ans) cout << x << "\n";
}

• Subtask 1: 10 / 10
• Subtask 2: 40 / 40
• Subtask 3: 25 / 25
• Subtask 4: 25 / 25