Submission #1000792

#	Time	Username	Problem	Language	Result	Execution time	Memory
1000792		vuavisao	September (APIO24_september)	C++17	75 / 100	221 ms	25296 KiB

september

#include "september.h"
 
#include <vector>

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

using ll = long long;
 
const int N = 100'000 + 10;
const int INF = 1'000'000'000;

struct FenWick {
	int n_node = 0;
	int tree[N];

	void resize(int n) { n_node = n; for (int i = 0; i <= n_node; ++ i) tree[i] = 0; }
	FenWick() {};
	FenWick(int n) { this->resize(n); };

	void Update(int idx, int val) {
		for ( ; idx <= n_node; idx += (idx & - idx)) tree[idx] += val;
		return;
	}

	int Query(int idx) {
		int res = 0;
		for ( ; idx > 0; idx -= (idx & - idx)) res += tree[idx];
		return res;
	}

	int Sum_to(int l, int r) {
		if (l > r) return 0;
		return Query(r) - Query(l - 1);
	}

	int kth(int val) {
		int res = 0, s = 0;
		for (int mask = 30; mask >= 0; -- mask) {
			int nxt = res | (1 << mask);
			if (nxt < n_node && s + tree[nxt] < val) {
				res = nxt;
				s += tree[nxt];
			}
		}
		++ res; return res;
	}
};

int n, m;
int parent[N];
vector<int> g[N];
int perRem[10][N];

int need[10][N];

namespace Order {
	int indexing[N];

	FenWick bit;

	void dfs(int u, int res[]) {
		int idx = indexing[u];
		res[idx] = idx;
		for (const auto& v : g[u]) {
			dfs(v, res);
			res[idx] = max(res[idx], res[indexing[v]]);
		}
	}
	
	void solve(int perRem[], int res[]) {
		for (int i = 1; i < n; ++ i) {
			indexing[perRem[i]] = i;
		}
		indexing[1] = 0;
		dfs(1, res);
	}
}

namespace One {
	bool check() {
		return (m == 1);
	}

	struct FenWickMax {
		int n_node = 0;
		int tree[N];

		void resize(int n) { n_node = n; for (int i = 0; i <= n_node; ++ i) tree[i] = -INF; }
		FenWickMax() {};
		FenWickMax(int n) { this->resize(n); };

		void Update(int idx, int val) {
			for ( ; idx > 0; idx -= (idx & - idx)) tree[idx] = max(tree[idx], val);
			return;
		}

		int Query(int idx) {
			int res = -INF;
			for ( ; idx <= n_node; idx += (idx & - idx)) res = max(res, tree[idx]);
			return res;
		}
	};

	vector<int> open[N];
	int dp[N];

	FenWick bit;
	FenWickMax bitMax;

	int solve() {
		for (int i = 0; i <= n + 1; ++ i) {
			vector<int>().swap(open[i]);
			dp[i] = -INF;
		}
		for (int i = 1; i < n; ++ i) {
			open[need[1][i]].push_back(i);
		}
		dp[0] = 0;
		bit.resize(n);
		for (int i = 1; i < n; ++ i) bit.Update(i, 1);

		bitMax.resize(n);
		for (int i = 1; i < n; ++ i) {
			for (const auto& idx : open[i]) bit.Update(idx, -1);
			bitMax.Update(i, dp[i - 1]);
			int cnt = bit.Query(i);
			int last = bit.kth(cnt) + (cnt != 0);
			if (last <= i) {
				dp[i] = bitMax.Query(last) + 1;
			}
		}
		return dp[n - 1];
	}
}

namespace Brute_force {
	bool check() {
		return (n <= 1'000);
	}

	unsigned seed = chrono::system_clock::now().time_since_epoch().count();
	mt19937_64 rng(seed); 

	ll Rand(ll a, ll b = 1ll * INF * INF) {
		return a + rng() % (b - a + 1);
	}

	bool can[1'010][1'010];
	ll base[N];
	ll Hash[10][N];

	vector<int> open[N];

	int exist[N];
	int dp[N];

	int solve() {
		srand(time(nullptr));
		for (int i = 0; i <= n + 1; ++ i) {
			dp[i] = -INF;
			exist[i] = 0;
			vector<int>().swap(open[i]);
		}
		for (int i = 0; i <= n + 1; ++ i) {
			for (int j = 0; j <= n + 1; ++ j) {
				can[i][j] = false;
			}
		}
		for (int i = 1; i <= n; ++ i) base[i] = Rand(1);
		for (int i = 1; i <= m; ++ i) {
			for (int j = 1; j < n; ++ j) {
				Hash[i][j] = base[perRem[i][j]];
				open[need[i][j]].push_back(j);
			}
		}
		for (int i = 1; i < n; ++ i) {
			ll xorHash[6];
			memset(xorHash, 0, sizeof(xorHash));
			for (int j = i; j < n; ++ j) {
				for (int k = 1; k <= m; ++ k) {
					xorHash[k] ^= Hash[k][j];
				}
				if (*min_element(xorHash + 1, xorHash + 1 + m) == *max_element(xorHash + 1, xorHash + 1 + m)) {
					can[i][j] = true;
				}
			}
		}
		dp[0] = 0;
		for (int i = 1; i < n; ++ i) {
			for (const auto& idx : open[i]) ++ exist[idx];
			for (int j = i; j >= 1; -- j) {
				if (exist[j] < m) break;
				if (can[j][i]) {
					// cout << j << ' ' << i << ' ' << dp[i] << ' ' << dp[j - 1] << '\n';
					dp[i] = max(dp[i], dp[j - 1] + 1);
				}
			}
		}
		return dp[n - 1];
	}
}
 
int solve(int N, int M, std::vector<int> F, std::vector<std::vector<int>> S) {
	n = N; m = M;
	for (int i = 0; i <= n + 1; ++ i) g[i].clear();
	for (int v = 2; v <= n; ++ v) {
		int u = F[v - 1] + 1;
		g[u].push_back(v);
		parent[v] = u;
	}
	for (int i = 0; i < m; ++ i) {
		for (int j = 0; j < n - 1; ++ j) {
			perRem[i + 1][j + 1] = S[i][j] + 1;
		}
	}

	for (int i = 1; i <= m; ++ i) {
		Order::solve(perRem[i], need[i]);
	}
 
	if (One::check()) {
		return One::solve();
	}
	if (Brute_force::check()) {
		return Brute_force::solve();
	}
	return 0;
}

• Subtask 1: 11 / 11
• Subtask 2: 14 / 14
• Subtask 3: 5 / 5
• Subtask 4: 9 / 9
• Subtask 5: 5 / 5
• Subtask 6: 11 / 11
• Subtask 7: 9 / 9
• Subtask 8: 11 / 11
• Subtask 9: 0 / 9
• Subtask 10: 0 / 16