Given a matrix of m x n elements (m rows, n columns), return all elements of the matrix in spiral order.
For example,
Given the following matrix:
[
1, 2, 3 ,
4, 5, 6 ,
7, 8, 9
]
You should return 1,2,3,6,9,8,7,4,5.
代码语言：txt复制 public List<Integer> spiralOrder(int[][] matrix) {
List<Integer> rt = new ArrayList<Integer>();
if (matrix == null || matrix.length == 0) {
return rt;
}
int startx = 0, endx = matrix.length - 1;
int starty = 0, endy = matrix[0].length - 1;
while (startx <= endx && starty <= endy) {
// 上边的行，从左向右
for (int y = starty; y <= endy; y ) {
rt.add(matrix[startx][y]);
}
// 右边的列，从上到下
for (int x = startx 1; x <= endx; x ) {
rt.add(matrix[x][endy]);
}
// 如果行或列遍历完，则退出循环
if (startx == endx || starty == endy) {
break;
}
// 下边的行，从右向左
for (int y = endy - 1; y >= starty; y--) {
rt.add(matrix[endx][y]);
}
// 左边的列，从下到上
for (int x = endx - 1; x >= startx 1; x--) {
rt.add(matrix[x][starty]);
}
startx ;
starty ;
endx--;
endy--;
}
return rt;
}
