Submission #380124

#TimeUsernameProblemLanguageResultExecution timeMemory
380124SuhaibSawalha1Rectangles (IOI19_rect)C++17
50 / 100
5088 ms639876 KiB
#include "rect.h"
#include <bits/stdc++.h>
using namespace std;

vector<int> lg{-1};

struct RMQ {
	vector<vector<int>> sp;
	void init (vector<int> &a) {
		int n = a.size();
		sp.resize(lg[n]+1, vector<int>(n));
		sp[0] = a;
		for (int i = 1; i < lg[n]+1; ++i) {
			for (int j = 0; j < n - (1 << i) + 1; ++j) {
				sp[i][j] = max(sp[i - 1][j], sp[i - 1][j + (1 << (i - 1))]);
			}
		}
	}
	int query (int l, int r) {
		assert(r >= l);
		int k = lg[r-l+1];
		return max(sp[k][l], sp[k][r - (1 << k) + 1]);
	}
};
 
long long count_rectangles(vector<vector<int>> a) {
	int n = a.size(), m = a[0].size();
	for (int i = 1; i <= max(n, m); ++i) {
		lg.push_back(lg.back()+!(i&(i-1)));
	}
	vector<RMQ> row(n), col(m);
	for (int i = 0; i < n; ++i) {
		row[i].init(a[i]);
	}
	for (int j = 0; j < m; ++j) {
		vector<int> p;
		for (int i = 0; i < n; ++i) {
			p.push_back(a[i][j]);
		}
		col[j].init(p);
	}
	long long ans = 0;
	for (int x = 1; x < n - 1; ++x) {
		for (int y = 1; y < m - 1; ++y) {
			for (int i = x; i < n  - 1; ++i) {
				if (a[i][y] >= a[i][y - 1] || a[i][y] >= a[x - 1][y]) {
					break;
				}
				bool bad = 0;
				for (int j = y; j < m - 1 && !bad; ++j) {
					bool good = 1;
					for (int l = x; l <= i && good; ++l) {
						int mx = row[l].query(y, j);
						good &= mx < a[l][j + 1] && mx < a[l][y - 1];
						bad |= mx >= a[l][y - 1];
					}
					for (int r = y; r <= j && good; ++r) {
						int mx = col[r].query(x, i);
						good &= mx < a[i + 1][r] && mx < a[x - 1][r];
						bad |= mx >= a[x - 1][r] || mx >= a[i + 1][r];
					}
					ans += good;
				}
			}
		}
	}
	return ans;
}
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