ProjectEuler incesption 中的错误答案？

Question

The goal of the code is to find the sum of all multiples of 3 and 5 under 1000 (natural numbers, so starting from 1).

My code:

sum_of_3 = 0
sum_of_5 = 0

for a in range (0, 1000, 3):
    sum_of_3 += a
print(sum_of_3)
Output: 166833

for b in range (0, 1000, 5)
    sum_of_5 += b
print (sum_of_5)
Output: 99500

total_sum = sum_of_3 + sum_of_5
print (total_sum)
Output: 266333

My output is wrong. The correct code and output is:

nums = range (1, 1000)
sumofmultiples = 0
for i in nums:
    if i % 3 == 0 or i % 5 == 0:
        sumofmultiples = i + sumofmultiples
print (sumofmultiples)
Output: 233168

Why am I getting a different answer?

Answer 1

When doing the collection of numbers in two seperate calculation, you add some numbers twice.

Have a look at 15, ist will be added onec since its a multipe of 3 and again, since its a multiple of 5.

If you want to keep your coed, you should check in your second for loop, whether the number ist dividable by 3.

Answer 2

You are calculating some value twice, For Example 15, 30, 45, 60, 75, 90. 105 and so on...

In your first loop you add some value such as 15, 30, 45 Then in your next loop you again add them!

In the correct code you can see there is a "Logical OR" operator which adding 15, 30, 45.... only for once

I hope you get it now Thank you.