Submission #1024071

#	Time	Username	Problem	Language	Result	Execution time	Memory
1024071		thinknoexit	Soccer Stadium (IOI23_soccer)	C++17	77.50 / 100	409 ms	71512 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 mx;
int l1[505][505], r1[505][505];
int L1[505], R1[505];
int dp[505][505], L[505][505], R[505][505];
int inter(int l1, int r1, int l2, int r2) {
    if (l1 > l2) {
        swap(l1, l2);
        swap(r1, r2);
    }
    // l1 <= l2
    if (r2 <= r1) return r2 - l2 + 1;
    if (r1 < l2) return 0;
    return r1 - l2 + 1;
}
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 > 500) return 0;
    for (int i = 1;i <= n;i++) {
        for (int j = 0;j <= n;j++) {
            if (f[i][j] == 1) l1[i][j] = j + 1;
            else l1[i][j] = l1[i][j - 1];
        }
        for (int j = n + 1;j >= 1;j--) {
            if (f[i][j] == 1) r1[i][j] = j - 1;
            else r1[i][j] = r1[i][j + 1];
        }
    }
    mx = 0;
    for (int c = 1;c <= n;c++) {
        for (int i = 1;i <= n;i++) {
            if (f[i][c]) dp[i][i] = -1e9, L[i][i] = L1[i] = -1, R[i][i] = R1[i] = -2;
            else {
                L1[i] = l1[i][c], R1[i] = r1[i][c];
                dp[i][i] = R1[i] - L1[i] + 1, L[i][i] = L1[i], R[i][i] = R1[i];
                mx = max(mx, dp[i][i]);
            }
        }
        for (int k = 1;k < n;k++) {
            for (int i = 1;i <= n - k;i++) {
                int j = i + k;
                L[i][j] = max(L[i + 1][j], L1[i]), R[i][j] = min(R[i + 1][j], R1[i]);
                dp[i][j] = -1e9;
                if (inter(L[i + 1][j], R[i + 1][j], L1[i], R1[i]) != 0) {
                    dp[i][j] = max(dp[i][j], dp[i + 1][j] + inter(L[i + 1][j], R[i + 1][j], L1[i], R1[i]));
                }
                if (inter(L[i][j - 1], R[i][j - 1], L1[j], R1[j]) != 0) {
                    dp[i][j] = max(dp[i][j], dp[i][j - 1] + inter(L[i][j - 1], R[i][j - 1], L1[j], R1[j]));
                }
                mx = max(mx, dp[i][j]);
            }
        }
    }
    return mx;
}

• 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: 7.5 / 30