练习 螺旋矩阵

给定一个包含 m x n 个元素的矩阵（m 行, n 列），请按照顺时针螺旋顺序，返回矩阵中的所有元素。

示例 1:

输入:
[
[ 1, 2, 3 ],
[ 4, 5, 6 ],
[ 7, 8, 9 ]
]
输出: [1,2,3,6,9,8,7,4,5]
示例 2:

输入:
[
[1, 2, 3, 4],
[5, 6, 7, 8],
[9,10,11,12]
]
输出: [1,2,3,4,8,12,11,10,9,5,6,7]

 public List<Integer> spiralOrder(int[][] matrix) {
        List<Integer> list = new ArrayList<>();
        if (matrix.length == 0) {
            return list;
        } else {
            int w = 0;
            int h = 0;
            int hm = matrix.length - 1;
            int wm = matrix[0].length -1;
            while (w <= wm && h <= hm) {
                for (int i = h;i <= wm; i++) {
                    list.add(matrix[h][i]);
                }
                if (list.size() == (matrix.length * matrix[0].length)){
                    return list;
                }
                for (int i = h + 1; i <= hm;i++) {
                    list.add(matrix[i][wm]);
                }
                if (list.size() == (matrix.length * matrix[0].length)){
                    return list;
                }
                for (int i = wm - 1;i >= h;i--) {
                    list.add(matrix[hm][i]);
                }
                if (list.size() == (matrix.length * matrix[0].length)){
                    return list;
                }
                for (int i = hm - 1;i > h; i--) {
                    list.add(matrix[i][w]);
                }
                if (list.size() == (matrix.length * matrix[0].length)){
                    return list;
                }

                w++;h++;hm--;wm--;
            }

        }

        return list;

    }