Submission #1050152

#	Time	Username	Problem	Language	Result	Execution time	Memory
1050152		BuzzyBeez	Regions (IOI09_regions)	C++17	100 / 100	1905 ms	82556 KiB

regions

#pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("arch=skylake")
#include <bits/stdc++.h>
using namespace std;

vector<int> adj[200008];
int color[200008];
vector<int> occ[25008], occ2[25008];
int tin[200008], tout[200008], euler[200008];
vector<int> ans[25008]; int hrank[25008];
int upd[200008], dp[200008];

void add_edge(int u, int v) {adj[u].push_back(v); adj[v].push_back(u);}

int timer = 0;
void DFS_EulerTour(int u) {
	tin[u] = ++timer; euler[timer] = u;
	for (int v : adj[u]) DFS_EulerTour(v);
	tout[u] = timer;
}

int get(int c, int l, int r) {
	if (l > r) return 0;
	return upper_bound(occ2[c].begin(), occ2[c].end(), r) - lower_bound(occ2[c].begin(), occ2[c].end(), l);
}

signed main() {
	int n, R, q, u, v, r1, r2, res; cin >> n >> R >> q >> color[1];
	for (u = 2; u <= n; ++u) cin >> v >> color[u], adj[v].push_back(u);
	DFS_EulerTour(1);
	// for (int i = 1; i <= n; ++i) cout << tin[i] << ' ' << tout[i] << '\n';
	for (u = 1; u <= n; ++u) occ[color[u]].push_back(u);
	int S = sqrt(3.0 * n * R / (q * (__lg(n) + 1)));
	vector<int> heavy;
	for (int c = 1; c <= R; ++c) if (occ[c].size() > S) heavy.push_back(c), hrank[c] = heavy.size();
	for (int c = 1; c <= R; ++c) ans[c].resize(heavy.size() + 1);
	for (int c : heavy) {
		for (int u : occ[c]) ++upd[tin[u] + 1], --upd[tout[u] + 1];
		for (int i = 1; i <= n; ++i) dp[i] = dp[i - 1] + upd[i];
		for (int i = 1; i <= n; ++i) ans[color[euler[i]]][hrank[c]] += dp[i];
		for (int i = 1; i <= n; ++i) dp[i] = 0, upd[i] = 0;
	}
	for (int c = 1; c <= R; ++c) {
		for (int u : occ[c]) occ2[c].push_back(tin[u]);
		sort(occ2[c].begin(), occ2[c].end());
	}
	while (q--) {
		cin >> r1 >> r2; 
		if (occ[r1].size() > S) cout << ans[r2][hrank[r1]] << endl;
		else {
			res = 0;
			for (int u : occ[r1]) res += get(r2, tin[u] + 1, tout[u]);
			cout << res << endl;
		}
	}
}

Compilation message (stderr)

regions.cpp: In function 'int main()':
regions.cpp:35:49: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   35 |  for (int c = 1; c <= R; ++c) if (occ[c].size() > S) heavy.push_back(c), hrank[c] = heavy.size();
      |                                   ~~~~~~~~~~~~~~^~~
regions.cpp:49:22: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   49 |   if (occ[r1].size() > S) cout << ans[r2][hrank[r1]] << endl;
      |       ~~~~~~~~~~~~~~~^~~

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