Submission #291863

#	Time	Username	Problem	Language	Result	Execution time	Memory
291863		keko37	Rectangles (IOI19_rect)	C++14	100 / 100	4948 ms	676324 KiB

rect

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

using namespace std;

typedef long long llint;
typedef pair <int, int> pi;

const int MAXN = 2505;
const int INF = 1000000007;

int n, m;
int a[MAXN][MAXN];
int lef[MAXN][MAXN], rig[MAXN][MAXN], upp[MAXN][MAXN], dwn[MAXN][MAXN];
vector <int> valr[MAXN][MAXN], valc[MAXN][MAXN];
vector < pair <pi, pi> > sol;

void precompute_row (int r) {
	vector <int> st;
	vector <pi> seg;
	for (int c = 0; c < m; c++) {
		while (!st.empty() && a[r][st.back()] <= a[r][c]) st.pop_back();
		lef[r][c] = (st.empty() ? -1 : st.back());
		st.push_back(c);
	}
	st.clear();
	for (int c = m - 1; c >= 0; c--) {
		while (!st.empty() && a[r][st.back()] <= a[r][c]) st.pop_back();
		rig[r][c] = (st.empty() ? -1 : st.back());
		st.push_back(c);
	}
	for (int c = 0; c < m; c++) {
		if (lef[r][c] != -1 && rig[r][c] != -1) seg.push_back({lef[r][c] + 1, rig[r][c] - 1});
	}
	sort(seg.begin(), seg.end());
	seg.erase(unique(seg.begin(), seg.end()), seg.end());
	for (auto par : seg) {
		valr[par.first][par.second].push_back(r);
	}
}

void precompute_col (int c) {
	vector <int> st;
	vector <pi> seg;
	for (int r = 0; r < n; r++) {
		while (!st.empty() && a[st.back()][c] <= a[r][c]) st.pop_back();
		upp[r][c] = (st.empty() ? -1 : st.back());
		st.push_back(r);
	}
	st.clear();
	for (int r = n - 1; r >= 0; r--) {
		while (!st.empty() && a[st.back()][c] <= a[r][c]) st.pop_back();
		dwn[r][c] = (st.empty() ? -1 : st.back());
		st.push_back(r);
	}
	for (int r = 0; r < n; r++) {
		if (upp[r][c] != -1 && dwn[r][c] != -1) seg.push_back({upp[r][c] + 1, dwn[r][c] - 1});
	}
	sort(seg.begin(), seg.end());
	seg.erase(unique(seg.begin(), seg.end()), seg.end());
	for (auto par : seg) {
		valc[par.first][par.second].push_back(c);
	}
}

inline int upit_row (int r, int c1, int c2) {
	return upper_bound(valr[c1][c2].begin(), valr[c1][c2].end(), r) - valr[c1][c2].begin();
}

inline int sum_row (int r1, int r2, int c1, int c2) {
	if (r1 == 0) return upit_row(r2, c1, c2);
	return upit_row(r2, c1, c2) - upit_row(r1 - 1, c1, c2);
}

inline int upit_col (int c, int r1, int r2) {
	return upper_bound(valc[r1][r2].begin(), valc[r1][r2].end(), c) - valc[r1][r2].begin();
}

inline int sum_col (int r1, int r2, int c1, int c2) {
	if (c1 == 0) return upit_col(c2, r1, r2);
	return upit_col(c2, r1, r2) - upit_col(c1 - 1, r1, r2);
}

bool check (int r1, int r2, int c1, int c2) {
	return sum_row(r1, r2, c1, c2) == r2 - r1 + 1 && sum_col(r1, r2, c1, c2) == c2 - c1 + 1;
}

llint count_rectangles (vector<vector<int>> A) {
	n = A.size(), m = A[0].size();
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			a[i][j] = A[i][j];
		}
	}
	for (int r = 0; r < n; r++) precompute_row(r);
	for (int c = 0; c < m; c++) precompute_col(c);
	for (int r = 1; r < n - 1; r++) {
		for (int c = 1; c < m - 1; c++) {
			if (lef[r][c] != -1 && rig[r][c] != -1 && upp[r][c] != -1 && dwn[r][c] != -1) {
				if (check(upp[r][c] + 1, dwn[r][c] - 1, lef[r][c] + 1, rig[r][c] - 1)) {
					sol.push_back({{upp[r][c] + 1, dwn[r][c] - 1}, {lef[r][c] + 1, rig[r][c] - 1}});
				}
			}
		}
	}
	sort(sol.begin(), sol.end());
	sol.erase(unique(sol.begin(), sol.end()), sol.end());
	return sol.size();
}

• 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