3循环排人

j = [i for i in range(1,42)]

j

[1,
 2,
 3,
 4,
 5,
 6,
 7,
 8,
 9,
 10,
 11,
 12,
 13,
 14,
 15,
 16,
 17,
 18,
 19,
 20,
 21,
 22,
 23,
 24,
 25,
 26,
 27,
 28,
 29,
 30,
 31,
 32,
 33,
 34,
 35,
 36,
 37,
 38,
 39,
 40,
 41]

k = 0
while len(j)>2:
    i = 0
    while i<len(j):
        k += 1
        if k == 3:
            j.remove(j[i])
            k = 0
        else:
            i += 1
print(j)
    

[16, 31]