@param matrix int整型二维数组

@return int整型一维数组

class Solution:
def spiralOrder(self , matrix ):
# write code here
if not matrix:return []
m=len(matrix)
n=len(matrix[0])

    i,j=0,-1
    ans=1
    res=[]
    while m>0 and n>0 :
        for _ in range(n):
            j+=ans*1
            res.append(matrix[i][j])

        for _ in range(m-1):
            i+=ans*1
            res.append(matrix[i][j])

        m-=1
        n-=1
        ans*=-1
    return res