Submission #737683

#	Time	Username	Problem	Language	Result	Execution time	Memory
737683		rnl42	Rectangles (IOI19_rect)	C++14	100 / 100	3784 ms	459856 KiB

rect

#include "rect.h"
#include <stack>
#include <algorithm>
using namespace std;

enum {
	TOP = 0,
	BOTTOM = 1,
	LEFT = 2,
	RIGHT = 3,
};

struct Case {
	int next[4] = {-1, -1, -1, -1};
	bool hasrect() {
		return next[0] != -1 && next[1] != -1 && next[2] != -1 && next[3] != -1;
	}
};

struct Rect1d {
	int a, b, w = 1;
	bool operator<(const Rect1d& other) const {
		return a == other.a ? b < other.b : a < other.a;
	}
	bool operator==(const Rect1d& other) const {
		return a == other.a && b == other.b;
	}
};

struct Rectangle {
	int r1, c1, r2, c2;
	bool operator<(const Rectangle& other) const {
		if (r1 != other.r1)
			return r1 < other.r1;
		if (c1 != other.c1)
			return c1 < other.c1;
		if (r2 != other.r2)
			return r2 < other.r2;
		if (c2 != other.c2)
			return c2 < other.c2;
		return false;
	}
	bool operator==(const Rectangle& other) const {
		return r1 == other.r1 && c1 == other.c1 && r2 == other.r2 && c2 == other.c2;
	}
};

long long count_rectangles(vector<vector<int>> A) {
	const int R = A.size(), C = A[0].size();

	vector<vector<Case>> cases(R, vector<Case>(C));
	stack<int> dec_seq;
	for (int r = 0; r < R; r++) {
		for (int c = 0; c < C; c++) {
			while (!dec_seq.empty() && A[r][dec_seq.top()] < A[r][c]) {
				dec_seq.pop();
			}
			if (!dec_seq.empty() && A[r][dec_seq.top()] > A[r][c]) cases[r][c].next[LEFT] = dec_seq.top();
			dec_seq.push(c);
		}
		while (!dec_seq.empty()) dec_seq.pop();
		for (int c = C-1; c >= 0; c--) {
			while (!dec_seq.empty() && A[r][dec_seq.top()] <= A[r][c]) {
				dec_seq.pop();
			}
			if (!dec_seq.empty()) cases[r][c].next[RIGHT] = dec_seq.top();
			dec_seq.push(c);
		}
		while (!dec_seq.empty()) dec_seq.pop();
	}

	for (int c = 0; c < C; c++) {
		for (int r = 0; r < R; r++) {
			while (!dec_seq.empty() && A[dec_seq.top()][c] < A[r][c]) {
				dec_seq.pop();
			}
			if (!dec_seq.empty() && A[dec_seq.top()][c] > A[r][c]) cases[r][c].next[TOP] = dec_seq.top();
			dec_seq.push(r);
		}
		while (!dec_seq.empty()) dec_seq.pop();
		for (int r = R-1; r >= 0; r--) {
			while (!dec_seq.empty() && A[dec_seq.top()][c] <= A[r][c]) {
				dec_seq.pop();
			}
			if (!dec_seq.empty()) cases[r][c].next[BOTTOM] = dec_seq.top();
			dec_seq.push(r);
		}
		while (!dec_seq.empty()) dec_seq.pop();
	}

	vector<Rectangle> rects;
	for (int r = 0; r < R; r++) {
		for (int c = 0; c < C; c++) {
			if (cases[r][c].hasrect()) {
				rects.push_back({cases[r][c].next[TOP]+1, cases[r][c].next[LEFT]+1, cases[r][c].next[BOTTOM]-1, cases[r][c].next[RIGHT]-1});
			}
		}
	}
	sort(rects.begin(), rects.end());
	rects.resize(unique(rects.begin(), rects.end()) - rects.begin());

	vector<vector<Rect1d>> rect1ds[2];
	rect1ds[0].resize(R);
	rect1ds[1].resize(C);
	for (int r = 0; r < R; r++) {
		for (int c = 0; c < C; c++) {
			if (cases[r][c].next[LEFT] != -1 && cases[r][c].next[RIGHT] != -1) {
				Rect1d newr = {cases[r][c].next[LEFT]+1, cases[r][c].next[RIGHT]-1};
				if (r > 0) {
					auto it = lower_bound(rect1ds[0][r-1].begin(), rect1ds[0][r-1].end(), newr);
					if (it != rect1ds[0][r-1].end() && *it == newr) {
						newr.w = 1+it->w;
					}
				}
				rect1ds[0][r].push_back(newr);
			}
		}
		sort(rect1ds[0][r].begin(), rect1ds[0][r].end());
	}

	for (int c = 0; c < C; c++) {
		for (int r = 0; r < R; r++) {
			if (cases[r][c].next[TOP] != -1 && cases[r][c].next[BOTTOM] != -1) {
				Rect1d newr = {cases[r][c].next[TOP]+1, cases[r][c].next[BOTTOM]-1};
				if (c > 0) {
					auto it = lower_bound(rect1ds[1][c-1].begin(), rect1ds[1][c-1].end(), newr);
					if (it != rect1ds[1][c-1].end() && *it == newr) {
						newr.w = 1+it->w;
					}
				}
				rect1ds[1][c].push_back(newr);
			}
		}
		sort(rect1ds[1][c].begin(), rect1ds[1][c].end());
	}

	int ans = 0;
	for (auto& r : rects) {
		auto& v = rect1ds[0][r.r2];
		auto it = lower_bound(v.begin(), v.end(), Rect1d{r.c1, r.c2});
		if (it != v.end() && *it == Rect1d{r.c1, r.c2} && it->w >= r.r2-r.r1+1) {
			auto& v = rect1ds[1][r.c2];
			auto it = lower_bound(v.begin(), v.end(), Rect1d{r.r1, r.r2});
			if (it != v.end() && *it == Rect1d{r.r1, r.r2} && it->w >= r.c2-r.c1+1) {
				ans++;
			}
		}
	}

	return ans;
}

• 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