Submission #1270927

#	Time	Username	Problem	Language	Result	Execution time	Memory
1270927		thewizardman	Regions (IOI09_regions)	C++20	100 / 100	3420 ms	32864 KiB

regions

#include <bits/stdc++.h>
using namespace std;
#define thres 500

int n, r, q, p, h[200001], r1, r2, timer, tin[200001], tout[200001], pre[500][25001], cnt[500];
vector<int> adj[200001];
vector<int> v1[200001], v2[25001], big;

int comp(int x) { return lower_bound(big.begin(), big.end(), x) - big.begin(); }

void dfs(int u, int p) {
  tin[u] = timer++;
  for (int i = 0; i < big.size(); i++) pre[i][h[u]] += cnt[i];
  if (v1[h[u]].size() >= thres) cnt[comp(h[u])]++;
  for (auto v: adj[u]) if (v != p) dfs(v, u);
  if (v1[h[u]].size() >= thres) cnt[comp(h[u])]--;
  tout[u] = timer;
}

int main() {
  ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
  cin >> n >> r >> q;
  cin >> h[1];
  v1[h[1]].push_back(1);
  for (int i = 2; i <= n; i++) {
    cin >> p >> h[i];
    adj[p].push_back(i);
    v1[h[i]].push_back(i);
  }
  for (int i = 1; i <= r; i++) if (v1[i].size() >= thres) big.push_back(i);
  dfs(1, 0);
  for (int i = 1; i <= n; i++) v2[h[i]].push_back(tin[i]);
  for (int i = 1; i <= r; i++) sort(v2[i].begin(), v2[i].end());
  for (int i = 0; i < q; i++) {
    int ans = 0;
    cin >> r1 >> r2;
    if (v1[r1].size() < thres) {
      for (auto e: v1[r1]) ans += lower_bound(v2[r2].begin(), v2[r2].end(), tout[e]) - lower_bound(v2[r2].begin(), v2[r2].end(), tin[e]);
      cout << ans << endl;
    } else {
      cout << pre[comp(r1)][r2] << endl;
    }
  }
}

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