完全遍历

l = ["一","二","三","四"]
i = 0
list_all = []
for i in range(i,len(l)):
    i = i
    outstr = ''
    list_a = []
    for i in range(i,len(l)):
        outstr += l[i]
        list_a.append(outstr)
    list_all.extend(list_a)
set_all = set(list_all)
print(set_all)
# {'一'，'一二'，'一二三'，'一二三四'，'二'，'二三'，'二三四'，'三'，'三四'，'四'}