Leetcode-994 Rotting Oranges(腐烂的橘子)

#define _for(i,a,b) for(int i = (a);i < (b);i ++)
class Solution
{
    public:
        int orangesRotting(vector<vector<int>>& grid)
        {
            int left = 0;
            int sz1 = grid.size();
            int sz2 = grid[0].size();
            _for(i,0,sz1)
                _for(j,0,sz2)
                    if(grid[i][j]==1)
                        left ++;
            
            int prev = left;
            int rnt = 0;
            while(left)
            {
                prev = left;
                _for(i,0,sz1)
                    _for(j,0,sz2)
                    {
                        if(grid[i][j]==2)
                        {
                            if(i+1<sz1&&grid[i+1][j]==1)
                            {
                                left--;
                                grid[i+1][j]=-1;
                            }
                            if(i-1>=0&&grid[i-1][j]==1)
                            {
                                left--;
                                grid[i-1][j]=-1;
                            }
                            if(j-1>=0&&grid[i][j-1]==1)
                            {
                                left--;
                                grid[i][j-1]=-1;
                            }
                            if(j+1<sz2&&grid[i][j+1]==1)
                            {
                                left--;
                                grid[i][j+1]=-1;
                            }
                        }
                    }
                    
                _for(i,0,sz1)
                    _for(j,0,sz2)
                        if(grid[i][j]==-1)
                            grid[i][j] = 2;
                rnt ++;
                if(prev==left)
                    return -1;
            }
            return rnt;
        }
};

 原则上来说，应该用BFS，看了一下数据范围，决定无脑暴力撸过