LeetCode Hot100. 994.腐烂的橘子

class Solution {
public:
    int orangesRotting(vector<vector<int>>& grid) {
        int total = 0;
        int m = grid.size();
        int n = grid[0].size();
        deque<pair<int, int>> queue;
        for(int i = 0; i < m; i++){
            for(int j = 0; j < n; j++){
                if(grid[i][j] == 1){
                    total++;
                }else if(grid[i][j] == 2){
                    queue.push_back({i, j});
                }
            }
        }
        int depth = 0;
        while(total > 0 && !queue.empty()){
            int size = queue.size();
            while(size--){
                pair<int, int> cur = queue.front();
                queue.pop_front();
                int i = cur.first;
                int j = cur.second;
                if(i > 0 && grid[i - 1][j] == 1){
                    grid[i - 1][j] = 2;
                    total--;
                    queue.push_back({i - 1, j});
                }
                if(i + 1 < m && grid[i + 1][j] == 1){
                    grid[i + 1][j] = 2;
                    total--;
                    queue.push_back({i + 1, j});
                }
                if(j > 0 && grid[i][j - 1] == 1){
                    grid[i][j - 1] = 2;
                    total--;
                    queue.push_back({i, j - 1});
                }
                if(j + 1 < n && grid[i][j + 1] == 1){
                    grid[i][j + 1] = 2;
                    total--;
                    queue.push_back({i, j + 1});
                }
            }
            depth++;
        }
        if(total != 0) return -1;
        return depth;
    }
};