题目
Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order.
解题思路
根据方向和下一个填充的位置的对应，找到下一个位置，如果这个位置出边界或已经被填过，则转换方向
代码
class Solution:
def generateMatrix(self, n: int) -> List[List[int]]:
res = [[0] * n for _ in range(n)]
directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]
curx = cury = curd = 0
for i in range(1, n * n + 1):
res[curx][cury] = i
newx, newy = curx + directions[curd][0], cury + directions[curd][1]
if newx < 0 or newx >= n or newy < 0 or newy >= n or res[newx][newy]:
curd = (curd + 1) % 4
curx += directions[curd][0]
cury += directions[curd][1]
return res
