Count Unguarded Cells in the Grid

class Solution {
    public int countUnguarded(int m, int n, int[][] guards, int[][] walls) {
        
        int grid[][] = new int[m][n];
        // guard = 1, wall = -1

        for(int[] guard : guards) {
            grid[guard[0]][guard[1]] = 1;
        }
        for(int[] wall : walls) {
            grid[wall[0]][wall[1]] = -1;
        }

        int dirs[][] = {{1,0},{-1,0},{0,1},{0,-1}};
        int count = 0;

        for(int i=0; i<guards.length; i++) {

            int row = guards[i][0];
            int col = guards[i][1];

            for(int dir[] : dirs) {

                int r = row + dir[0];
                int c = col + dir[1];
                while(r>=0 && r<m && c>=0 && c<n && grid[r][c]!=1 && grid[r][c]!=-1 ) {
                    if(grid[r][c]==0) {
                        count++; // guarding this cell
                        grid[r][c] = 2;
                    }
                    r = r + dir[0];
                    c = c + dir[1];
                }
            }

        }

        return m*n - count - guards.length - walls.length;

    }
}