[Python] 삼각달팽이

from itertools import chain
def solution(n):
    myarray = [[0 for i in range(n)] for j in range(n)]
    number = 1
    x,y = -1,0
    for i in range(n):
        for j in range(i,n):
            if i%3==0:
                x+=1
            elif i%3==1:
                y+=1
            elif i%3==2:
                x-=1
                y-=1
            myarray[x][y]=number
            number+=1
    answer=[i for i in chain(*myarray) if i!=0]
    return answer