Submission #647905

#	Time	Username	Problem	Language	Result	Execution time	Memory
647905		1zaid1	T-Covering (eJOI19_covering)	C++17	15 / 100	66 ms	24200 KiB

covering

#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long
#define double long double
#define F first
#define S second

const int M = 3e3+5;
vector<int> node[M];
int vis[M], dp[M][4];
vector<vector<int>> ar, x, buff;
vector<pair<int, int>> v={{0,0}}, p = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}};

void dfs(int s) {
    vis[s] = true;
    vector<int> z;
    for (int i:node[s]) {
        if (!vis[i]) {
            z.push_back(i);
            dfs(i);
        }
    }
    
    for (auto [dx, dy]:p) buff[v[s].F+dx][v[s].S+dy]++;
    for (int a = 0; a < 4; a++) {
        buff[v[s].F+p[a].F][v[s].S+p[a].S]--;

        for (auto u:z) {
            if (dp[s][a] < 0) break;
            for (auto [dx, dy]:p) buff[v[u].F+dx][v[u].S+dy]++;
            
            int mx = -1;
            for (int b = 0; b < 4; b++) {
                if (dp[u][b] < 0) continue;
                buff[v[u].F+p[b].F][v[u].S+p[b].S]--;
                bool ok = true;
                for (auto [dx, dy]:p) {
                    if (buff[v[u].F+dx][v[u].S+dy] == 2 ||
                        buff[v[s].F+dx][v[s].S+dy] == 2) {
                        ok = false;
                        break;
                    }
                }

                if (ok) {
                    mx = max(mx, dp[u][b]);
                }

                buff[v[u].F+p[b].F][v[u].S+p[b].S]++;
            }

            if (mx >= 0) dp[s][a] += mx;
            else dp[s][a] = mx;
            for (auto [dx, dy]:p) buff[v[u].F+dx][v[u].S+dy]--;
        }

        if (dp[s][a] >= 0) {
            for (auto [dx, dy]:p) dp[s][a] += ar[v[s].F+dx][v[s].S+dy];
            dp[s][a] += ar[v[s].F][v[s].S]-ar[v[s].F+p[a].F][v[s].S+p[a].S];
        }

        buff[v[s].F+p[a].F][v[s].S+p[a].S]++;
    }

    for (auto [dx, dy]:p) buff[v[s].F+dx][v[s].S+dy]--;
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);

    int n, m;
    cin >> n >> m;
    x = vector<vector<int>>(n+5, vector<int>(m+5, 0));
    ar = vector<vector<int>>(n+5, vector<int>(m+5, 0));
    buff = vector<vector<int>>(n+5, vector<int>(m+5, 0));

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) cin >> ar[i][j];
    int k;
    cin >> k;
    for (int i = 1; i <= k; i++) {
        int a, b;
        cin >> a >> b;
        a++;b++;

        x[a][b] = i;
        v.push_back({a, b});
    }

    for (auto [a, b]:v) {
        for (int i = a-2; i <= a+2; i++) {
            for (int j = b-2; j <= b+2; j++) {
                if (i == a && j == b || i < 1 || j < 1 || i > n || j > m || !x[i][j]) continue;
                node[x[a][b]].push_back(x[i][j]);
            }
        }
    }

    int ans = 0;
    for (int i = 1; i <= k; i++) {
        if (!vis[i]) {
            dfs(i);
            if (*max_element(dp[i], dp[i]+4) == -1) {
                cout << "No" << endl;
                return 0;
            }

            ans += *max_element(dp[i], dp[i]+4);
        }
    }

    // for (int i = 1; i <= k; i++) {
    //     cout << i << ": ";
    //     for (auto j:dp[i]) cout << j << ' '; cout << endl;
    // }

    cout << ans << endl;

    return 0;
}
/*
5 6
7 3 8 1 0 9
4 6 2 5 8 3
1 9 7 3 9 5
2 6 8 4 5 7
3 8 2 7 3 6
3
1 1
2 2
3 4

5 6
7 3 8 1 0 9
4 6 2 5 8 3
1 9 7 3 9 5
2 6 8 4 5 7
3 8 2 7 3 6
3
1 1
2 2
3 3
*/

Compilation message (stderr)

covering.cpp: In function 'int main()':
covering.cpp:94:28: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   94 |                 if (i == a && j == b || i < 1 || j < 1 || i > n || j > m || !x[i][j]) continue;
      |                     ~~~~~~~^~~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 10 / 10
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 30