Submission #415253

#	Time	Username	Problem	Language	Result	Execution time	Memory
415253		Alex_tz307	Regions (IOI09_regions)	C++17	100 / 100	4933 ms	27184 KiB

regions

#include <bits/stdc++.h>

using namespace std;

const int MAXN = 2e5;
const int MAXR = 25 * 1e3;
const int BLOCK = 450;
int r[MAXN], timer, in[MAXN], out[MAXN], ind[MAXR], cnt[BLOCK], root[BLOCK][MAXR];
vector<int> G[MAXN], R[MAXR], pos[MAXR], large;
bitset<MAXN> is_large;

void dfs1(int u) {
  in[u] = ++timer;
  pos[r[u]].emplace_back(in[u]);
  for (int v : G[u])
    dfs1(v);
  out[u] = timer;
}

void dfs2(int u) {
  for (auto region : large)
    root[ind[region]][r[u]] += cnt[ind[region]];
  if (is_large[r[u]])
    ++cnt[ind[r[u]]];
  for (int v : G[u])
    dfs2(v);
  if (is_large[r[u]])
    --cnt[ind[r[u]]];
}

int solve(int r1, int r2) {
  int ans = 0;
  for (int u : R[r1]) {
    int st = lower_bound(pos[r2].begin(), pos[r2].end(), in[u]) - pos[r2].begin();
    int dr = upper_bound(pos[r2].begin(), pos[r2].end(), out[u]) - pos[r2].begin();
    ans += dr - st;
  }
  return ans;
}

int main() {
  int n, m, Q;
  cin >> n >> m >> Q;
  for (int v = 0; v < n; ++v) {
    if (v == 0) {
      cin >> r[0];
      --r[0];
      R[r[0]].emplace_back(0);
      continue;
    }
    int u;
    cin >> u >> r[v];
    --r[v];
    G[u - 1].emplace_back(v);
    R[r[v]].emplace_back(v);
  }
  dfs1(0);
  for (int i = 0; i < m; ++i)
    if ((int)R[i].size() > BLOCK) {
      is_large[i] = true;
      ind[i] = large.size();
      large.emplace_back(i);
    }
  dfs2(0);
  for (int q = 0; q < Q; ++q) {
    int r1, r2;
    cin >> r1 >> r2;
    --r1, --r2;
    if ((int)R[r1].size() > BLOCK)
      cout << root[ind[r1]][r2] << '\n';
    else cout << solve(r1, r2) << '\n';
    cout.flush();
  }
  return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 85 / 85