短路

class Solution:
    def spiralOrder(self, matrix):
        """
        :type matrix: List[List[int]]
        :rtype: List[int]
        """
        res=[]
        self.spiralMatrix(matrix,res)
        return res
    def spiralMatrix(self,matrix,res):
        if matrix==[] or matrix[0]==[]:
            return
        m,n=len(matrix),len(matrix[0])
        if m==0:
            return
        elif m==1:
            res.extend(matrix[0])
        elif n==1:
            res.extend([ele[0] for ele in matrix])
        else:
            res.extend(matrix[0])
            res.extend([matrix[i][-1] for i in range(1,len(matrix)-1)])
            res.extend([ele for ele in matrix[-1][::-1]])
            res.extend([matrix[i][0] for i in range(len(matrix)-2,0,-1)])
            matrix=[matrix[i][1:len(matrix[0])-1] for i in range(1,len(matrix)-1)]
            self.spiralMatrix(matrix, res)