54 Spiral Matrix

Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.

Example 1:

Input:
[
 [ 1, 2, 3 ],
 [ 4, 5, 6 ],
 [ 7, 8, 9 ]
]
Output: [1,2,3,6,9,8,7,4,5]

 public List<Integer> spiralOrder(int[][] matrix) {
        
        List<Integer> list = new ArrayList();

        int row = matrix.length;  
        if(row ==0 )return list;
        int col = matrix[0].length;
        
        
       
        
        int l = 0 , r = col-1 , t = 0 ,  b = row-1 , d = 0;
        
        while(l<=r && t<=b){
            if(d==0){
                for(int i=l;i<=r;i++){
                    list.add(matrix[t][i]);
                }
                d=1;t++;
            }else if(d==1){
                  for(int i=t;i<=b;i++){
                      list.add(matrix[i][r]);
                  }    
                d=2;r--;
            }else if (d==2){
                for(int i =r;i>=l;i--){
                    list.add(matrix[b][i]);
                }
                d=3;b--;
            }else if (d==3){
                for(int i = b;i>=t;i--){
                     list.add(matrix[i][l]);
                }
               d=0;l++; 
            }
        }
        return list;

    }