Steward

分享是一種喜悅、更是一種幸福

程式語言 - LeetCode - C++ - 994. Rotting Oranges

---

題目：


解答：

class Solution {
public:
    int orangesRotting(vector<vector<int>>& grid) {
        int r = 0;
        queue<pair<int, int>> q;
        int row_size = grid.size();
        int col_size = grid[0].size();

        for (int i = 0; i < grid.size(); i++) {
            for (int j = 0; j < grid[i].size(); j++) {
                if (grid[i][j] == 2) {
                    q.emplace(i, j);
                }
            }
        }

        while (!q.empty()) {
            int valid = 0;
            int size = q.size();
            int dir[] = { -1, 0, 1, 0, -1 };

            for (int i= 0; i < size; i ++) {
                auto pos = q.front();
                q.pop();

                for (int j = 0; j < 4; j++) {
                    int row = pos.first + dir[j];
                    int col = pos.second + dir[j + 1];

                    if ((row >= 0) &&
                        (row < row_size) &&
                        (col >= 0) &&
                        (col < col_size) &&
                        (grid[row][col] == 1))
                    {
                        valid = 1;
                        grid[row][col] = 2;
                        q.emplace(row, col);
                    }
                }
            }
            r += valid;
        }

        for (int i = 0; i < grid.size(); i++) {
            for (int j = 0; j < grid[i].size(); j++) {
                if (grid[i][j] == 1) {
                    return -1;
                }
            }
        }

        return r;
    }
};