问题描述
给你一个正整数 n ,生成一个包含 1 到 n2 所有元素,且元素按顺时针顺序螺旋排列的 n x n 正方形矩阵 matrix 。
示例 1:
输入:n = 3
输出:[[1,2,3],[8,9,4],[7,6,5]]
示例 2:
输入:n = 1
输出:[[1]]
提示:
- 1 <= n <= 20
来源:力扣(LeetCode)
链接:https://leetcode-cn.com/problems/spiral-matrix-ii
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思路分析及代码实现
还是采用按层模拟的方法
一层一层往里遍历
class Solution:
def generateMatrix(self, n: int) -> List[List[int]]:
res = [[0 for i in range(n)] for j in range(n)]
left = 0
right = n-1
top = 0
bottom = n-1
li = [i for i in range(1, n**2+1)]
num = 1
while left <= right and top <= bottom:
for i in range(left, right+1):
res[top][i] = num
num += 1
for j in range(top+1, bottom+1):
res[j][right] = num
num += 1
if left < right and top < bottom:
for k in range(right-1, left, -1):
res[bottom][k] = num
num += 1
for l in range(bottom, top, -1):
res[l][left] = num
num += 1
left += 1
right -= 1
top += 1
bottom -= 1
return res