Code
total = 0
lst = [[20, 12, 1, 5], [25, 10, 7], [9, 30]]
for i in range(len(lst)):
for j in range(len(lst[i])):
total += lst[i][j]
Memory
total
0
i
0
j
0
lst
[
0:
[20, 12, 1, 5]
1:
[25, 10, 7]
2:
[9, 30]
]
Visual
