Submission #1010400

#	Time	Username	Problem	Language	Result	Execution time	Memory
1010400		thinknoexit	Soccer Stadium (IOI23_soccer)	C++17	65.50 / 100	268 ms	70692 KiB

soccer

#include "soccer.h"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 2020;
int n;
int f[N][N], qs[N][N];
int l[N], r[N];
// check if all empty cell are regular stadium
bool all_can() {
    for (int i = 1;i <= n;i++) {
        for (int j = 1;j <= n + 1;j++) {
            if (f[i][j - 1] != f[i][j]) {
                if (!l[i]) l[i] = j;
                else if (!r[i]) r[i] = j - 1;
                else return 0;
            }
        }
    }
    for (int j = 1;j <= n;j++) {
        int cnt = 0;
        for (int i = 1;i <= n;i++) {
            cnt += f[i - 1][j] != f[i][j];
        }
        if (cnt > 2) return 0;
    }
    for (int i = 1;i <= n;i++) {
        if (l[i] == 0) continue;
        for (int j = 1;j <= n;j++) {
            if (l[j] == 0) continue;
            bool ch = (l[i] <= l[j] && r[j] <= r[i]) || (l[j] <= l[i] && r[i] <= r[j]);
            if (!ch) return 0;
        }
    }
    return 1;
}
int dp[33][33][33][33], mx;
int biggest_stadium(int NN, vector<vector<int>> F) {
    n = NN;
    int empty_cell = 0;
    for (int i = 1;i <= n;i++) {
        f[0][i] = f[n + 1][i] = f[i][0] = f[i][n + 1] = 1;
        for (int j = 1;j <= n;j++) {
            f[i][j] = F[i - 1][j - 1];
            qs[i][j] = qs[i][j - 1] + f[i][j];
            empty_cell += f[i][j] == 0;
        }
    }
    if (all_can()) return empty_cell;
    if (empty_cell == n * n - 1) {
        int mx = 0;
        for (int i = 1;i <= n && !mx;i++) {
            for (int j = 1;j <= n && !mx;j++) {
                if (f[i][j]) {
                    mx = max(mx, (i - 1) * n + (j - 1) * n - (i - 1) * (j - 1));
                    mx = max(mx, (n - i) * n + (j - 1) * n - (n - i) * (j - 1));
                    mx = max(mx, (i - 1) * n + (n - j) * n - (i - 1) * (n - j));
                    mx = max(mx, (n - i) * n + (n - j) * n - (n - i) * (n - j));
                }
            }
        }
        return mx;
    }
    if (n > 30) return 0;
    // dp[i][j][l][r] -> soccer stadium from i -> j can only place in (l, r) interval
    memset(dp, 0xc0, sizeof dp);
    // Base Case
    for (int i = 1;i <= n;i++) {
        for (int l = 1;l <= n;l++) {
            for (int r = l;r <= n;r++) {
                if (qs[i][r] - qs[i][l - 1] == 0) dp[i][i][l][r] = r - l + 1;
            }
        }
    }
    // Calcualte DP
    for (int k = 1;k < n;k++) {
        for (int i = 1;i <= n - k;i++) {
            int j = i + k;
            for (int l = 1;l <= n;l++) {
                for (int r = l;r <= n;r++) {
                    int& v = dp[i][j][l][r];
                    for (int l1 = 1;l1 <= l;l1++) {
                        for (int r1 = r;r1 <= n;r1++) {
                            if (qs[j][r] - qs[j][l - 1] == 0)
                                v = max(v, dp[i][j - 1][l1][r1] + r - l + 1);
                            if (qs[i][r] - qs[i][l - 1] == 0)
                                v = max(v, dp[i + 1][j][l1][r1] + r - l + 1);
                        }
                    }
                }
            }
        }
    }
    for (int i = 1;i <= n;i++) for (int j = 1;j <= n;j++)
        for (int l = 1;l <= n;l++) for (int r = 1;r <= n;r++) {
            mx = max(mx, dp[i][j][l][r]);
        }
    return mx;
}

• Subtask 0: 0 / 0
• Subtask 1: 6 / 6
• Subtask 2: 8 / 8
• Subtask 3: 22 / 22
• Subtask 4: 18 / 18
• Subtask 5: 4 / 16
• Subtask 6: 7.5 / 30