Submission #655252

#	Time	Username	Problem	Language	Result	Execution time	Memory
655252		d4xn	Regions (IOI09_regions)	C++17	85 / 100	8068 ms	27304 KiB

regions

#pragma GCC optimize ("Ofast")
#pragma GCC target ("avx2")
#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define all(x) x.begin(), x.end()
#define ii pair<int, int>
#define pb push_back
#define vi vector<int>
#define vvi vector<int>
#define vii vector<ii>

const int N = 200000, R1 = 25000, R2 = 500;

int n, r, q, curr;
int reg[N], sz[N], pre[N], idx[N];
ll ans[R2][R2];
vi adj[N], from[R1], pos[R1];

void dfs(int u) {
  sz[u] = 1;
  pre[curr] = reg[u];
  pos[reg[u]].pb(curr);
  idx[u] = curr;
  curr++;

  for (int &v : adj[u]) {
    dfs(v);
    sz[u] += sz[v];
  }
}

int query(int a, int b, int c) {
  int l = lower_bound(all(pos[c]), a) - pos[c].begin();
  int r = upper_bound(all(pos[c]), b) - pos[c].begin();
  return r-l;
}

signed main() {
  ios::sync_with_stdio(false); cin.tie(nullptr);

  cin >> n >> r >> q;

  for (int i = 0; i < n; i++) {
    if (i) {
      int x;
      cin >> x;
      x--;
      adj[x].pb(i);
    }
  
    cin >> reg[i];
    reg[i]--;
    from[reg[i]].pb(i);
  }

  curr = 0;
  dfs(0);

  if (r <= 500) {
    // precalc all queries
    for (int i = 0; i < r; i++) {
      for (int j = 0; j < r; j++) {
        if (i == j) continue;
        ans[i][j] = 0;
        for (int &u : from[i]) {
          ans[i][j] += query(idx[u], idx[u] + sz[u] - 1, j);
        }
      }
    }
  }

  while (q--) {
    int x, y;
    cin >> x >> y;
    x--; y--;
    if (r <= 500) {
      cout << ans[x][y] << "\n";
      cout.flush();
    }
    else {
      ll cnt = 0;
      for (int &u : from[x]) {
        cnt += query(idx[u], idx[u] + sz[u] - 1, y);
      }
      cout << cnt << "\n";
      cout.flush();
    }   
  }
}

• Subtask 1: 15 / 15
• Subtask 2: 70 / 85