Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
For example, Given n = 3, You should return the following matrix:
[
[ 1, 2, 3 ],
[ 8, 9, 4 ],
[ 7, 6, 5 ]
]
依照题意，设置填充边界，沿着边界填写。
见程序注释
Given an integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.
For example, Given n = 3, You should return the following matrix:
[
[ 1, 2, 3 ],
[ 8, 9, 4 ],
[ 7, 6, 5 ]
]
依照题意，设置填充边界，沿着边界填写。
见程序注释