Submission #878866

#	Time	Username	Problem	Language	Result	Execution time	Memory
878866		SanguineChameleon	Soccer Stadium (IOI23_soccer)	C++17	100 / 100	572 ms	172624 KiB

soccer

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

const int maxN = 2e3 + 20;
int A[maxN][maxN];
int prv[maxN][maxN][2];
int top[maxN][maxN];
int bottom[maxN][maxN];
vector<pair<int, int>> group[maxN];
int dp[maxN][maxN];

int biggest_stadium(int N, vector<vector<int>> _A) {
	for (int i = 1; i <= N; i++) {
		for (int j = 1; j <= N; j++) {
			A[i][j] = _A[i - 1][j - 1];
		}
	}
	for (int i = 0; i <= N + 1; i++) {
		A[0][i] = 1;
		A[N + 1][i] = 1;
		A[i][0] = 1;
		A[i][N + 1] = 1;
	}
	for (int i = 1; i <= N; i++) {
		for (int j = 1; j <= N; j++) {
			for (int k = 0; k < 2; k++) {
				if (A[i][j] == k) {
					prv[i][j][k] = j;
				}
				else {
					prv[i][j][k] = prv[i][j - 1][k];
				}
			}
		}
	}
	for (int j = 0; j <= N; j++) {
		top[0][j] = 0;
		bottom[N + 1][j] = N + 1;
	}
	for (int i = 1; i <= N + 1; i++) {
		for (int j = 0; j <= N + 1; j++) {
			if (A[i - 1][j] == 1) {
				top[i][j] = i - 1;
			}
			else {
				top[i][j] = top[i - 1][j];
			}
		}
	}
	for (int i = N; i >= 1; i--) {
		for (int j = 0; j <= N; j++) {
			if (A[i + 1][j] == 1) {
				bottom[i][j] = i + 1;
			}
			else {
				bottom[i][j] = bottom[i + 1][j];
			}
		}
	}
	for (int i = N; i >= 1; i--) {
		for (int j = 1; j <= N; j++) {
			if (A[i][j] == 0) {
				if (A[i][j - 1] == 0) {
					top[i][j] = max(top[i][j], top[i][j - 1]);
					bottom[i][j] = min(bottom[i][j], bottom[i][j - 1]);
				}
				group[j - prv[i][j][1]].emplace_back(i, j);
			}
		}
	}
	int res = 0;
	for (int W = N; W >= 1; W--) {
		for (auto [i, j]: group[W]) {
			if (top[i][j] + 1 <= top[i][prv[i][j][1]]) {
				dp[top[i][prv[i][j][1]]][j] = max(dp[top[i][prv[i][j][1]]][j], dp[i][j]);
				continue;
			}
			int L = prv[i][j][1] + 1;
			int R = j;
			int T = top[i][j] + 1;
			int B = bottom[i][j] - 1;
			if (top[B + 1][R + 1] + 1 <= T) {
				continue;
			}
			res = max(res, dp[i][j] + (R - L + 1) * (B - T + 1));
			for (int iter = 0; iter < 2; iter++) {
				int row = (iter ? B + 1 : T - 1);
				if (row < 1 || row > N) {
					continue;
				}
				int nxtR = prv[row][R][0];
				while (nxtR >= L) {
					int nxtL = max(L, prv[row][nxtR][1] + 1);
					int nxt_row = (nxtL == L ? i : row); 
					dp[nxt_row][nxtR] = max(dp[nxt_row][nxtR], dp[i][j] + ((R - L + 1) - (nxtR - nxtL + 1)) * (B - T + 1));
					nxtR = prv[row][nxtL - 1][0];
				}
			}
		}
	}
	return res;
}

• Subtask 0: 0 / 0
• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 22 / 22
• Subtask 4: 18 / 18
• Subtask 5: 16 / 16
• Subtask 6: 30 / 30