Given a positive integer n, generate an n x n matrix filled with elements from 1 to n2 in spiral order.
Example 1:
Input: n = 3
Output: [[1,2,3],[8,9,4],[7,6,5]]
Example 2:
Input: n = 1
Output: [[1]]
Constraints:
-
1 <= n <= 20
SOLUTION:
class Solution:
def generateMatrix(self, n: int) -> List[List[int]]:
matrix = [[-1 for i in range(n)] for j in range(n)]
ctr = 0
direction = 0
x, y = 0, 0
while ctr < n * n:
if matrix[x][y] == -1:
ctr += 1
matrix[x][y] = ctr
switch = False
if direction == 0:
if (y + 1) < n and matrix[x][y + 1] == -1:
y += 1
else:
switch = True
elif direction == 1:
if (x + 1) < n and matrix[x + 1][y] == -1:
x += 1
else:
switch = True
elif direction == 2:
if (y - 1) >= 0 and matrix[x][y - 1] == -1:
y -= 1
else:
switch = True
else:
if (x - 1) >= 0 and matrix[x - 1][y] == -1:
x -= 1
else:
switch = True
if switch:
direction = (direction + 1) % 4
return matrix
Top comments (0)