54.螺旋矩阵

matrix, simulation, https://leetcode.cn/problems/spiral-matrix/

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。

示例 1：

输入：matrix = [[1,2,3],[4,5,6],[7,8,9]]
输出：[1,2,3,6,9,8,7,4,5]

示例 2：

输入：matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
输出：[1,2,3,4,8,12,11,10,9,5,6,7]

提示：

m == matrix.length
n == matrix[i].length
1 <= m, n <= 10
-100 <= matrix[i][j] <= 100

python

from typing import List


class Solution:
    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
        if not matrix or not matrix[0]:
            return []

        m, n = len(matrix), len(matrix[0])
        visited = [[False] * n for _ in range(m)]
        result = []

        directions = [(0, 1), (1, 0), (0, -1), (-1, 0)]
        x, y = 0, 0
        dir_idx = 0  # 初始方向为向右
        for _ in range(m * n):
            result.append(matrix[x][y])
            visited[x][y] = True

            dx, dy = directions[dir_idx]
            next_x, next_y = x + dx, y + dy

            # 检查边界条件和访问状态，如果合法，更新到下一个位置
            if 0 <= next_x < m and 0 <= next_y < n and not visited[next_x][next_y]:
                x, y = next_x, next_y
            else:
                dir_idx = (dir_idx + 1) % 4
                dx, dy = directions[dir_idx]
                x, y = x + dx, y + dy

        return result

if __name__ == "__main__":
    sol = Solution()
    print(sol.spiralOrder([[1,2,3,4],[5,6,7,8],[9,10,11,12]]))

54.螺旋矩阵 ​

54.螺旋矩阵