循环的新手问题

Question

I am brain dead on trying to do the following task in Python(3.) Please help.

Write a loop that calculates the total of the following series of numbers: 1/30 + 2/29 + 3/27 +⋯+ 29/2 + 30/1.

for numerator in range(1, 31, 1):
    denominator = (31 - numerator)
    quotient = numerator / denominator
    print(quotient)

I can produce the quotient of each but am lost on how to efficiently find the sum.

Answer 1

For efficiency:

In [794]: sum(i*1.0/(31-i) for i in range(1, 31)) # i*1.0 is for backward compatibility with python2
Out[794]: 93.84460105853213

If you have to do that in a loop explicitly, see @Bill's hints ;)

Answer 2

You're almost there, so I'll give you a few hints.

# initialize a total variable to 0 before the loop

for numerator in range(1, 31, 1):
    denominator = (31 - numerator)
    quotient = numerator / denominator
    print(quotient)
    # update the total inside the loop (add the quotient to the total)

# print the total when the loop is complete

If you want to see a more Pythonic (idomatic) solution, see zhangxaochen's answer. ;)

Answer 3

total = 0
for numerator in range(1, 31, 1):
    denominator = (31 - numerator)
    quotient = numerator / denominator
    print(quotient)
    total += quotient
print/return(total)

Be aware you are going to have some rounding going on and may get an answer you aren't expecting.

Answer 4

Do this to keep track of summation.

total = 0

for numerator in range(1, 31, 1):
    denominator = (31 - numerator)
    quotient = numerator / denominator
    total = total + quotient

print(total)