不使用python中的sum函数对2D列表的行求和

Question

I have a listed called numbers and I am writing code to sum the rows then sum the result of those sums (ie sum the column). I am supposed to write the code without the sum function. What I have so far is pasted below. It gives me close to the right output but is just slightly off and I don't know what the deal is.

total=0

for row in numbers:
  for i in row:
      total+=int(i)
  print(total)

grandtotal=0
for cols in row:
  grandtotal+=total
print(grandtotal)

Answer 1

You need to reset total back to zero for each row. And since you aren't saving the row totals anywhere you need to accumulate the grandtotal at the end of each row loop, not in a separate loop

numbers = [
    [1, 1, -2],
    [-1, -2, -3],
    [1, 1, 1],
]

grandtotal = 0
for row in numbers:
    total = 0
    for i in row:
        total += i
    print(total)
    grandtotal += total
print(grandtotal)

output

0
-6
3
-3