Submission #439246

#	Time	Username	Problem	Language	Result	Execution time	Memory
439246		elazarkoren	T-Covering (eJOI19_covering)	C++17	55 / 100	277 ms	12100 KiB

covering

#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#define x first
#define y second
#define chkmin(a, b) a = min(a, b)
#define chkmax(a, b) a = max(a, b)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> pii;
typedef vector<pii> vii;
typedef vector<bool> vb;
typedef vector<vb> vvb;

const int infinity = 1e9;

int dir_x[] = {-1, 1, 0, 0, -1, -1, 1, 1};
int dir_y[] = {0, 0, -1, 1, -1, 1, -1, 1};

set<pii> touch;
int ans = 0;

bool Dfs(vvi &graph, int node, vvi &board, vii &special, int parent, vb &visited) {
    int x = special[node].x, y = special[node].y;
    ans += board[x][y];
    touch.insert({x - 1, y}), touch.insert({x + 1, y}), touch.insert({x, y + 1}), touch.insert({x, y - 1});
    visited[node] = true;
    for (int neighbor : graph[node]) {
        if (neighbor == parent) continue;
        if (visited[neighbor]) return false;
        if (!Dfs(graph, neighbor, board, special, node, visited)) return false;
    }
    return true;
}

int main() {
    int n, m;
    cin >> n >> m;
    vvi board(n, vi(m));
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            cin >> board[i][j];
        }
    }
    int k;
    cin >> k;
    vii special(k);
    vvi visited(n, vi(m));
    for (int i = 0; i < k; i++) {
        cin >> special[i].x >> special[i].y;
        visited[special[i].x][special[i].y] = i + 1;
    }
    vb finished(k);
    vvi graph(k);
    for (int i = 0; i < k; i++) {
        int x = special[i].x, y = special[i].y;
        int sum = board[x][y], bad = 4;
        if (x && !visited[x - 1][y]) {
            sum += board[x - 1][y];
            bad--;
        }
        if (x < n - 1 && !visited[x + 1][y]) {
            sum += board[x + 1][y];
            bad--;
        }
        if (y && !visited[x][y - 1]) {
            sum += board[x][y - 1];
            bad--;
        }
        if (y < m - 1 && !visited[x][y + 1]) {
            sum += board[x][y + 1];
            bad--;
        }
        int bad2 = 0;
        for (int j = 4; j < 8; j++) {
            x += dir_x[j], y += dir_y[j];
            if (0 <= x && x < n && 0 <= y && y < m && visited[x][y]) {
                bad2++;
            }
            x -= dir_x[j], y -= dir_y[j];
        }
        if (bad + bad2 > 1) {
            cout << "No";
            return 0;
        } else if (bad == 1 && !bad2) {
            finished[i] = true;
            ans += sum;
        } else {
            if (bad2) {
                touch.insert({x, y}), touch.insert({x - 1, y}), touch.insert({x + 1, y}), touch.insert({x, y + 1}), touch.insert({x, y - 1});
                finished[i] = true;
            } else {
                if (x > 1 && visited[x - 2][y]) {
                    graph[i].push_back(visited[x - 2][y] - 1);
                }
                if (y > 1 && visited[x][y - 2]) {
                    graph[i].push_back(visited[x][y - 2] - 1);
                }
                if (x < n - 2 && visited[x + 2][y]) {
                    graph[i].push_back(visited[x + 2][y] - 1);
                }
                if (y < m - 2 && visited[x][y + 2]) {
                    graph[i].push_back(visited[x][y + 2] - 1);
                }
            }
        }
    }
    for (pii p : touch) {
        ans += board[p.x][p.y];
    }
    touch.clear();
    for (int i = 0; i < k; i++) {
        if (finished[i]) continue;
        if (!Dfs(graph, i, board, special, -1, finished)) {
            cout << "No";
            return 0;
        }
        int min_val = infinity;
        for (pii p : touch) {
            ans += board[p.x][p.y];
            chkmin(min_val, board[p.x][p.y]);
        }
        ans -= min_val;
        touch.clear();
    }
    cout << ans;
}

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