lists = [[] for i in range(3)] # 创建的是多行三列的二维列表
for i in range(3):
  lists[0].append(i)
for i in range(5):
  lists[1].append(i)
for i in range(7):
  lists[2].append(i)
print("lists is:", lists)
# lists is: [[0, 1, 2], [0, 1, 2, 3, 4], [0, 1, 2, 3, 4, 5, 6]]

sum_0 = 0
for i in range(len(lists)):
  for j in range(len(lists[i])):
    print(lists[i][j])
    sum_0 += lists[i][j]
print("The sum_0 of Lists:", sum_0)

# 0
# 1
# 2
# 0
# 1
# 2
# 3
# 4
# 0
# 1
# 2
# 3
# 4
# 5
# 6
# The sum of Lists: 34

sum_1 = 0
for i in lists:
  for j in i:
    sum_1 += j

print("The sum_1 of Lists:", sum_1)
# The sum_1 of Lists: 34