深色模式
54 旋转矩阵
给你一个 m 行 n 列的矩阵 matrix ，请按照 顺时针螺旋顺序 ，返回矩阵中的所有元素。
题解
记录访问过的位置存放在 visited 中，顺时针访问，遇到边界或者遇到访问过的位置，就改变方向。
1. 时间复杂度：
2. 空间复杂度：
py
class Solution:
def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
m = len(matrix)
n = len(matrix[0])
visited = [[0 for x in range(n)] for x in range(m)]
answer = []
i = 0
j = 0
direction = 'right'
while i >= 0 and i < m and j >= 0 and j < n:
if visited[i][j] == 1:
break
answer.append(matrix[i][j])
visited[i][j] = 1
# 计算下一个位置
if direction == "right":
# 更换方向
if j == n-1 or visited[i][j + 1] == 1:
direction = 'down'
# 此时 i 是否安全？
i += 1
else:
j += 1
elif direction == "left":
if j == 0 or visited[i][j -1] == 1:
direction = "up"
i -= 1
else:
j -= 1
elif direction == "up":
if i == 0 or visited[i-1][j] == 1:
direction = 'right'
j += 1
else:
i -= 1
elif direction == "down":
if i == m -1 or visited[i+1][j] == 1:
direction = "left"
j -= 1
else:
i += 1
return answer同样的解法，看看官方解法代码简洁
py
class Solution:
def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
if not matrix or not matrix[0]:
return list()
rows, columns = len(matrix), len(matrix[0])
visited = [[False] * columns for _ in range(rows)]
total = rows * columns
order = [0] * total
directions = [[0, 1], [1, 0], [0, -1], [-1, 0]]
row, column = 0, 0
directionIndex = 0
for i in range(total):
order[i] = matrix[row][column]
visited[row][column] = True
nextRow, nextColumn = row + directions[directionIndex][0], column + directions[directionIndex][1]
if not (0 <= nextRow < rows and 0 <= nextColumn < columns and not visited[nextRow][nextColumn]):
directionIndex = (directionIndex + 1) % 4
row += directions[directionIndex][0]
column += directions[directionIndex][1]
return order
作者：力扣官方题解
链接：https://leetcode.cn/problems/spiral-matrix/solutions/275393/luo-xuan-ju-zhen-by-leetcode-solution/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。解法二：分层 先外层访问，后内容访问，查看官方代码
py
class Solution:
def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
if not matrix or not matrix[0]:
return list()
rows, columns = len(matrix), len(matrix[0])
order = list()
left, right, top, bottom = 0, columns - 1, 0, rows - 1
while left <= right and top <= bottom:
for column in range(left, right + 1):
order.append(matrix[top][column])
for row in range(top + 1, bottom + 1):
order.append(matrix[row][right])
if left < right and top < bottom:
for column in range(right - 1, left, -1):
order.append(matrix[bottom][column])
for row in range(bottom, top, -1):
order.append(matrix[row][left])
left, right, top, bottom = left + 1, right - 1, top + 1, bottom - 1
return order
作者：力扣官方题解
链接：https://leetcode.cn/problems/spiral-matrix/solutions/275393/luo-xuan-ju-zhen-by-leetcode-solution/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。
``