面试题29. 顺时针打印矩阵（Python）

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]

class Solution:
    def spiralOrder(self, matrix: List[List[int]]) -> List[int]:
        if not matrix or len(matrix) == 0 or not matrix[0] or len(matrix[0]) == 0:
            return []
        left,right = 0,len(matrix[0])-1
        top,bottom = 0,len(matrix)-1

        result = []

        while True:
            for i in range(left,right+1):
                result.append(matrix[top][i])
            top+=1
            if top>bottom:
                break

            for i in range(top,bottom+1):
                result.append(matrix[i][right])
            right-=1
            if left>right:
                break

            for i in range(right,left-1,-1):
                result.append(matrix[bottom][i])
            bottom-=1
            if top>bottom:
                break
            
            for i in range(bottom,top-1,-1):
                result.append(matrix[i][left])
            left+=1
            if left>right:
                break
            
        return result