【Leetcode】剑指Offer 29：顺时针打印矩阵

输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字。
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]
限制：
0 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