【LeetCode热题100】【图论】腐烂的橘子

class Solution {
public:
    int rows, columns;
    vector<vector<int> > grid;

    bool isValid(int x, int y) {
        return x >= 0 && y >= 0 && x < rows && y < columns;
    }

    int orangesRotting(vector<vector<int> > &grid) {
        rows = grid.size();
        columns = grid[0].size();
        this->grid = move(grid);
        int ans = 0, fresh = 0;
        queue<pair<int, int> > pullte;
        for (int i = 0; i < rows; ++i)
            for (int j = 0; j < columns; ++j)
                if (this->grid[i][j] == 1)
                    ++fresh;
                else if (this->grid[i][j] == 2)
                    pullte.emplace(i, j);
        int move[4][2] = {{0, 1}, {0, -1}, {1, 0}, {-1, 0}};
        while (fresh > 0 && !pullte.empty()) {
            int scale = pullte.size();
            while (--scale >= 0) {
                for (int i = 0; i < 4; ++i) {
                    auto [x,y] = pullte.front();
                    x += move[i][0];
                    y += move[i][1];
                    if (isValid(x, y) && this->grid[x][y] == 1) {
                        this->grid[x][y] = 2;
                        pullte.emplace(x, y);
                        --fresh;
                    }
                }
                pullte.pop();
            }
            ++ans;
        }
        if (fresh > 0)
            return -1;
        return ans;
    }
};