Submission #840042

#	Time	Username	Problem	Language	Result	Execution time	Memory
840042		olnyfcxwps	Soccer Stadium (IOI23_soccer)	C++17	6 / 100	319 ms	47392 KiB

soccer

#include <iostream>
#include <vector>
using namespace std;

const int N = 30;
int n;
int tree[2000][2000];
bool seen[2000][2000];
int prefix[N][N];
int dp1[N][N][N];
int dp2[N][N][N];

bool are_empty(int row, int col1, int col2) {
    if (col1 == 0) {
        return prefix[row][col2] == 0;
    }
    return prefix[row][col2] == prefix[row][col1 - 1];
}

int solve_1() {
    int x = 0;
    int y = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (tree[i][j] == 1) {
                x = i;
                y = j;
            }
        }
    }
    x += 1;
    y += 1;
    int m = x * y;
    int t = x * (n - y + 1);
    if (t < m) {
        m = t;
    }
    t = (n - x + 1) * y;
    if (t < m) {
        m = t;
    }
    t = (n - x + 1) * (n - y + 1);
    if (t < m) {
        m = t;
    }
    return n * n - m;
}

int dp() {
    // init
    for (int i = 0; i < n; i++) {
        prefix[i][0] = tree[i][0];
        for (int j = 1; j < n; j++) {
            prefix[i][j] = prefix[i][j - 1] + tree[i][j];
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            for (int k = 0; k < n; k++) {
                dp1[i][j][k] = -1;
                dp2[i][j][k] = -1;
            }
        }
    }
    for (int j = 0; j < n; j++) {
        for (int k = j; k < n; k++) {
            // if all empty
            if (are_empty(0, j, k)) {
                dp1[0][j][k] = k - j + 1;
            }
        }
    }

    // dp from 1 to n - 1
    for (int i = 1; i < n; i++) {
        for (int j = 0; j < n; j++) {
            for (int k = j; k < n; k++) {
                // check base case
                if (are_empty(i, j, k)) {
                    dp1[i][j][k] = k - j + 1;
                } else {
                    continue;
                }
                for (int l = j; l <= k; l++) {
                    for (int m = l; m <= k; m++) {
                        // check if [l, m] are all empty
                        if (!are_empty(i - 1, l, m)) {
                            break;
                        }
                        // dp1
                        if (dp1[i - 1][l][m] != -1) {
                            int t = dp1[i - 1][l][m] + k - j + 1;
                            if (dp1[i][j][k] == -1 || dp1[i][j][k] < t) {
                                dp1[i][j][k] = t;
                            }
                        }
                    }
                }
            }
        }
    }

    for (int j = 0; j < n; j++) {
        for (int k = j; k < n; k++) {
            // if all empty
            if (are_empty(n - 1, j, k)) {
                dp2[n - 1][j][k] = k - j + 1;
            }
        }
    }

    // dp from n - 2 to 0
    for (int i = n - 2; i >= 0; i--) {
        for (int j = 0; j < n; j++) {
            for (int k = j; k < n; k++) {
                // check base case
                if (are_empty(i, j, k)) {
                    dp2[i][j][k] = k - j + 1;
                } else {
                    continue;
                }
                for (int l = j; l <= k; l++) {
                    for (int m = l; m <= k; m++) {
                        // check if [l, m] are all empty
                        if (!are_empty(i + 1, l, m)) {
                            break;
                        }
                        // dp2
                        if (dp2[i + 1][l][m] != -1) {
                            int t = dp2[i + 1][l][m] + k - j + 1;
                            if (dp2[i][j][k] == -1 || dp2[i][j][k] < t) {
                                dp2[i][j][k] = t;
                            }
                        }
                    }
                }
            }
        }
    }

    /*for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            for (int k = j; k < n; k++) {
                cout << i << " " << j << " " << k << " " << dp1[i][j][k] << "\n";
            }
        }
    }*/

    int ans = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            for (int k = j; k < n; k++) {
                if (ans < dp1[i][j][k]) {
                    ans = dp1[i][j][k];
                }
                if (ans < dp2[i][j][k]) {
                    ans = dp2[i][j][k];
                }
                /*if (dp1[i][j][k] != -1 && dp2[i][j][k] != -1) {
                    int t = dp1[i][j][k] + dp2[i][j][k] - (k - j + 1);
                    if (t > ans) {
                        ans = t;
                    }
                }*/
            }
        }
    }

    return ans;
}

void dfs(int r, int c) {
    seen[r][c] = true;
    if (r - 1 >= 0 && tree[r - 1][c] == 0 && !seen[r - 1][c]) {
        dfs(r - 1, c);
    }
    if (r + 1 < n && tree[r + 1][c] == 0 && !seen[r + 1][c]) {
        dfs(r + 1, c);
    }
    if (c - 1 >= 0 && tree[r][c - 1] == 0 && !seen[r][c - 1]) {
        dfs(r, c - 1);
    }
    if (c + 1 < n && tree[r][c + 1] == 0 && !seen[r][c + 1]) {
        dfs(r, c + 1);
    }
}

bool check() {
    int c = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            seen[i][j] = false;
        }
    }
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            if (tree[i][j] == 0) {
                if (!seen[i][j]) {
                    dfs(i, j);
                    c += 1;
                }
            }
        }
    }
    if (c != 1) {
        return false;
    }

    vector<int> s;
    vector<int> t;
    int longest = 0;
    int where = 0;
    for (int i = 0; i < n; i++) {
        bool seen = false;
        for (int j = 0; j < n;) {
            if (tree[i][j] == 0) {
                if (seen) {
                    return false;
                }
                seen = true;
                int k = j + 1;
                while (k < n && tree[i][k] == 0) {
                    k++;
                }
                s.push_back(j);
                t.push_back(k - 1);
                if (longest < k - j) {
                    longest = k - j;
                    where = i;
                }
                j = k;
            } else {
                j++;
            }
        }
    }

    for (int i = where - 1; i >= 0; i--) {
        if (s[i] < s[i + 1] || t[i] > t[i + 1]) {
            return false;
        }
    }
    for (int i = where + 1; i < n; i++) {
        if (s[i + 1] < s[i] || t[i + 1] > t[i]) {
            return false;
        }
    }

    for (int i = 0; i < s.size(); i++) {
        for (int j = i + 1; j < s.size(); j++) {
            if (s[i] < s[j] && t[i] < t[j]) {
                return false;
            }
            if (s[i] > s[j] && t[i] > t[j]) {
                return false;
            }
            if (s[i] > t[j]) {
                return false;
            }
            if (s[j] > t[i]) {
                return false;
            }
        }
    }

    return true;
}

// int biggest_stadium(int N, int[][] F)
int biggest_stadium(int X, vector<vector<int>> F) {
    n = X;
    int total = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            tree[i][j] = F[i][j];
            total += tree[i][j];
        }
    }
    if (total == 1) {
        return solve_1();
    }
    if (total == 0) {
        return n * n;
    }
    /*if (n > 30) {
        return 123;
    }*/

    if (check()) {
        return n * n - total;
    }

    return n * n - total - 1;

    /*int ans = dp();
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            int t = tree[i][j];
            tree[i][j] = tree[j][i];
            tree[j][i] = t;
        }
    }
    int another_ans = dp();
    if (another_ans > ans) {
        ans = another_ans;
    }
    return ans;*/
}

Compilation message (stderr)

soccer.cpp: In function 'bool check()':
soccer.cpp:249:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  249 |     for (int i = 0; i < s.size(); i++) {
      |                     ~~^~~~~~~~~~
soccer.cpp:250:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  250 |         for (int j = i + 1; j < s.size(); j++) {
      |                             ~~^~~~~~~~~~

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