Solution.cpp

class Solution {
public:
    int minimumVisitedCells(vector<vector<int>>& grid) {
        int m = grid.size(), n = grid[0].size();
        vector<vector<int>> dist(m, vector<int>(n, -1));
        using pii = pair<int, int>;
        priority_queue<pii, vector<pii>, greater<pii>> row[m];
        priority_queue<pii, vector<pii>, greater<pii>> col[n];
        dist[0][0] = 1;
        for (int i = 0; i < m; ++i) {
            for (int j = 0; j < n; ++j) {
                while (!row[i].empty() && grid[i][row[i].top().second] + row[i].top().second < j) {
                    row[i].pop();
                }
                if (!row[i].empty() && (dist[i][j] == -1 || row[i].top().first + 1 < dist[i][j])) {
                    dist[i][j] = row[i].top().first + 1;
                }
                while (!col[j].empty() && grid[col[j].top().second][j] + col[j].top().second < i) {
                    col[j].pop();
                }
                if (!col[j].empty() && (dist[i][j] == -1 || col[j].top().first + 1 < dist[i][j])) {
                    dist[i][j] = col[j].top().first + 1;
                }
                if (dist[i][j] != -1) {
                    row[i].emplace(dist[i][j], j);
                    col[j].emplace(dist[i][j], i);
                }
            }
        }
        return dist[m - 1][n - 1];
    }
};