妙啊

Nice. Also, will overflow sooner than O(n) solutions.

Very good utilization of mathematical theorems. Excellent answer.

chinese friends!!!

do you need to explain now? math soluation?

Love this solution, can someone explain me, what formula do we use to find all numbers that divide (by 3, for example) in any range?

you can use value ? func1() : func2(); instead of value == true ? func1() : func2();
becouse the value it's already boolean and you don't need to check it.

I was looking for this solution, great thinking.

Really nice using maths, but what about result for negative numbers == 0?

Thats a very illustrative example why some simple math can be extremly powerful.

I think it's fun

等差数列求和公式
集合容斥原理
结合在一块

wow I don't understand it but it is great

Please use spoiler flag next time.