Submission #535989

#	Time	Username	Problem	Language	Result	Execution time	Memory
535989		KoD	Rectangles (IOI19_rect)	C++17	100 / 100	2143 ms	322328 KiB

rect

#include <bits/stdc++.h>
#include "rect.h"

using ll = long long;
using namespace std;

struct fenwick {
	vector<int> data;
	explicit fenwick(const int n) : data(n + 1) {}
	void add(int i, const int x) {
		for (i += 1; i < (int)data.size(); i += i & -i) data[i] += x;
	}
	int pref(int i) const {
		int ret = 0;
		for (; i > 0; i -= i & -i) ret += data[i];
		return ret;
	}
	int fold(const int l, const int r) const {
		return pref(r) - pref(l);
	}
};

template <class F> vector<pair<int, int>> enumerate(const int n, const F& f) {
	vector<pair<int, int>> valid;
	vector<int> stack;
	for (int i = 0; i < n; ++i) {
		int sofar = 0;
		const int r = f(i);
		while (!stack.empty()) {
			const int j = stack.back();
			const int l = f(j);
			if (min(l, r) > sofar and i - j > 1) valid.emplace_back(j, i);
			if (l >= r) break;
			stack.pop_back();
			sofar = max(sofar, l);
		}
		stack.push_back(i);
	}
	return valid;
}

ll count_rectangles(vector<vector<int>> a) {
	const int n = a.size();
	const int m = a[0].size();
	if (n <= 2 or m <= 2) return 0;
	vector fix_down(n, vector<vector<int>>(m));
	for (int j = 0; j < m; ++j) {
		for (const auto& [u, d] : enumerate(n, [&](const int i) { return a[i][j]; })) {
			fix_down[d][j].push_back(u);
		}
	}
	vector<tuple<int, int, int>> lr;
	for (const auto& [l, r] : enumerate(m, [&](const int j) { return a[1][j]; })) {
		lr.emplace_back(l, r, 0);
	}
	vector valid_up(n, fenwick(m));
	int count = 0;
	for (int down = 2; down < n; ++down) {
		for (int j = 0; j < m; ++j) {
			for (const int up : fix_down[down][j]) valid_up[up].add(j, 1);
		}
		for (const auto& [l, r, u] : lr) {
			for (const int up : fix_down[down][l + 1]) {
				if (up < u) break;
				if (valid_up[up].fold(l + 1, r) == r - l - 1) count += 1;
			}
		}
		if (down + 1 < n) {
			vector<tuple<int, int, int>> next;
			int idx = 0;
			for (const auto& [l, r] : enumerate(m, [&](const int j) { return a[down][j]; })) {
				bool done = false;
				while (idx < (int)lr.size()) {
					const auto& [l0, r0, u] = lr[idx];
					if (l0 == l and r0 == r) {
						next.emplace_back(l, r, u);
						done = true;
						break;
					}
					if (r0 < r or (r0 == r and l0 > l)) {
						idx += 1;
					} else {
						break;
					}
				}
				if (!done) next.emplace_back(l, r, down - 1);
			}
			lr = std::move(next);
			for (int j = 0; j < m; ++j) {
				for (const int up : fix_down[down][j]) valid_up[up].add(j, -1);
			}
		}
	}
	return count;
}

• Subtask 1: 8 / 8
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 22 / 22
• Subtask 5: 10 / 10
• Subtask 6: 13 / 13
• Subtask 7: 28 / 28