Submission #1137130

#	Time	Username	Problem	Language	Result	Execution time	Memory
1137130		lucaskojima	Regions (IOI09_regions)	C++17	70 / 100	8100 ms	53724 KiB

regions

#include "bits/stdc++.h"
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()

using namespace std;
using ll = long long;
using pii = pair<int, int>;

const char nl = '\n';
const ll LINF = 0x3f3f3f3f3f3f3f3f;
const int INF = 0x3f3f3f3f;

int main() {
	ios::sync_with_stdio(0), cin.tie(0);

	int N, R, Q; cin >> N >> R >> Q;

	vector<vector<int>> adj(N + 1);
	vector<int> reg(N + 1), qnt(R + 1);

	cin >> reg[1];
	qnt[reg[1]]++;

	for (int i = 2; i <= N; i++) {
		int a, b; cin >> a >> b;
		adj[a].push_back(i);
		reg[i] = b;
		qnt[b]++;
	}

	// vertices de regioes pequenas
	vector<int> large_id(R + 1);
	const int C = 500;
	int RR = 0;

	for (int i = 1; i <= R; i++)
		if (qnt[i] > C) large_id[i] = ++RR;

	vector dp(N + 1, vector<int>(RR + 1));

	auto dfs = [&](auto dfs, int x) -> void {
		for (int k : adj[x]) {
			dfs(dfs, k);

			dp[x][large_id[reg[k]]]++;
			for (int v = 1; v <= RR; v++)
				dp[x][v] += dp[k][v];
		}
	}; dfs(dfs, 1);

	vector ans(RR + 1, vector<int>(RR + 1));

	for (int i = 1; i <= N; i++)
		for (int j = 1; j <= RR; j++)
			ans[large_id[reg[i]]][j] += dp[i][j];

	// vertices de regioes grandes
	vector<vector<int>> emp(R + 1);
	vector<int> tin(N + 1), tout(N + 1);
	int tcur = 0;

	auto euler = [&](auto euler, int x) -> void {
		tin[x] = ++tcur;
		emp[reg[x]].push_back(x);

		for (int k : adj[x])
			euler(euler, k);

		tout[x] = tcur;
	}; euler(euler, 1);

	auto calc = [&](int a, int b) -> int {
		vector<pii> line;
		for (int x : emp[a]) {
			line.push_back({tin[x], 1});
			line.push_back({tout[x], 3});
		}
		for (int y : emp[b])
			line.push_back({tin[y], 2});

		sort(all(line));

		int ans = 0, cnt = 0;
		for (auto [d, t] : line) {
			if (t == 1) cnt++;
			if (t == 2) ans += cnt;
			if (t == 3) cnt--;
		}
		return ans;
	};

	map<pii, int> memo;

	while (Q--) {
		int a, b; cin >> a >> b;

		if (large_id[a] && large_id[b]) {
			cout << ans[large_id[a]][large_id[b]] << endl;
		} else {
			if (memo[{a, b}] != 0) { cout << memo[{a, b}] << endl; continue; }

			int ans = calc(a, b);
			memo[{a, b}] = ans;
			cout << ans << endl;
		}
	}
	return 0;
}

• Subtask 1: 15 / 15
• Subtask 2: 55 / 85