rottenOrangesJava

class Solution {
    public int orangesRotting(int[][] grid) {
        if(grid == null || grid.length == 0) return 0;
        int rows = grid.length;
        int cols = grid[0].length;
        Queue<int[]> queue = new LinkedList<>();
        int count_fresh = 0;
        //Put the position of all rotten oranges in queue
        //count the number of fresh oranges
        for(int i = 0 ; i < rows ; i++) {
            for(int j = 0 ; j < cols ; j++) {
                if(grid[i][j] == 2) {
                    queue.offer(new int[]{i , j});
                }
                if(grid[i][j] != 0) {
                    count_fresh++;
                }
            }
        }
       
        if(count_fresh == 0) return 0;
        int countMin = 0, cnt = 0;
        int dx[] = {0, 0, 1, -1};
        int dy[] = {1, -1, 0, 0};
        
        //bfs starting from initially rotten oranges
        while(!queue.isEmpty()) {
            int size = queue.size();
            cnt += size; 
            for(int i = 0 ; i < size ; i++) {
                int[] point = queue.poll();
                for(int j = 0;j<4;j++) {
                    int x = point[0] + dx[j];
                    int y = point[1] + dy[j];
                    
                    if(x < 0 || y < 0 || x >= rows || y >= cols || grid[x][y] == 0 || grid[x][y] == 2) continue;
                    
                    grid[x][y] = 2;
                    queue.offer(new int[]{x , y});
                }
            }
            if(queue.size() != 0) {
                countMin++;
            }
        }
        return count_fresh == cnt ? countMin : -1;
    }
}