54. Spiral Matrix

class Solution {
    public List<Integer> spiralOrder(int[][] matrix) {
        int top = 0;
        int bottom = matrix.length-1;
        int left = 0;
        int right= matrix[0].length-1;
        
        List<Integer> res = new LinkedList<Integer>();
        
        while(true){
            for (int j = left; j<=right; j++){
                res.add(matrix[top][j]);
            }
            top++;
            if (top>bottom) break;
            
            for(int i = top; i<=bottom; i++){
                res.add(matrix[i][right]);
            }
            right--;
            if(left>right) break;
            
            for(int j = right; j>=left; j--){
                res.add(matrix[bottom][j]);
            }
            bottom--;
            if (top>bottom) break;
            
            for(int i=bottom; i>=top; i--){
                res.add(matrix[i][left]);
            }
            left++;
            if(left>right) break;
        }
        return res; 
    }
}