Leetcode-5040 Coloring A Border(边框着色)

const int dx[] = {1,-1,0,0};
const int dy[] = {0,0,1,-1};
#define _for(i,a,b) for(int i = (a);i < (b);i ++)
class Solution
{
    public:
        int vis[60][60];
        void go(vector<vector<int>>& grid, int r0, int c0, int color,int lo)
        {
            vis[r0][c0] = 1;
            grid[r0][c0] = -color;
            _for(i,0,4)
            {
                int nx = r0 + dx[i];
                int ny = c0 + dy[i];
                if(nx>=0 && nx<grid.size() && ny>=0 && ny<grid[0].size()
                && vis[nx][ny]==0 && grid[nx][ny]==lo)
                {
                    go(grid,nx,ny,color,lo);
                }
            }
        }
        vector<vector<int>> colorBorder(vector<vector<int>>& grid, int r0, int c0, int color)
        {
            memset(vis,0,sizeof(vis));
            int lo = grid[r0][c0];
            go(grid,r0,c0,color,lo);
            vector<pair<int,int>> vv;
            _for(i,0,grid.size())
                _for(j,0,grid[i].size())
                    if(grid[i][j]<0)
                    {
                        if(i==0 || i==grid.size()-1 || j==0 || j==grid[i].size()-1)
                            continue;
                        if(grid[i+1][j]==-color && grid[i-1][j]==-color && grid[i][j+1]==-color && grid[i][j-1]==-color)
                            vv.push_back({i,j});
                      //      grid[i][j] = lo;
                    }
            _for(i,0,vv.size())
                grid[vv[i].first][vv[i].second] = lo;
            _for(i,0,grid.size())
                _for(j,0,grid[i].size())
            {
                if(grid[i][j]<0)
                    grid[i][j] = -grid[i][j];
            }
            
            return grid;
        }
};