Problem 1: Multiples of 3 and 5

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Problem 1: Multiples of 3 and 5

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

解题思路：

找出所有3和5的倍数，不超过最大数n，去重求和即可。

 

l = []  # 存放3和5倍数的数
n = 1000  # 最大数
for i in range(1, n):
    if 3*i >= n:  # 如果大于最大数，终止
        break
    l.append(3*i)
for i in range(1, n):
    if 5*i >= n:
        break
    l.append(5*i)
l = set(l)  # 去重，譬如15 30之类的
print(sum(l))

%time %run ol001.py
233168
Wall time: 2 ms