[TIL]Day 200

프로그래머스 삼각달팽이

import itertools
def solution(n):
    answer = [[0]*i for i in range(1,n+1)]
    num = 1
    for i in range((n+2)//3):
        #n -1 + i*-3
        iter_num = n -1 + i * -3
        for j in range(i*2,i*2+iter_num):
            answer[j][i] = num
            num += 1
        for j in range(i,iter_num+i):
            answer[-(i+1)][j] = num
            num += 1
        for j in range(-(i+1),-iter_num-(i+1),-1):
            answer[j][-(i+1)] = num
            num += 1
        if answer[i*2][i] == 0:
            answer[i*2][i] = num
    return list(itertools.chain(*answer))