Since tourist reached 4000 rating a lot of people said congratulations to him, even MikeMirzayanov made a blog congratulating him, and never did tourist say thank you to anyone. I never seen such arrogance and bad manners in my life.

So there is this known problem: you have 2 arrays (let's say a and b) both of size n and you have to arrange them in such a way that the value $$$\sum_{i=1}^{n}a_{i}b_{i}$$$ is as small as possible. Intuitively, an idea is to pair the biggest element in a with the smallest in b, the second largest in a with the second smallest in b and so on. But I would like to see some sort of proof because this only relies on intuition. Thanks in advance.

Example: initially a = {3, 1, 1}, b = {6, 5, 4}. After performing the algorithm a = {3, 1, 1}, b = {4, 5, 6}. Answer is 3*4 + 1*5 + 1*6 = 23

Hi so I want to practice some problems on Timus that would be the equivalent of 1400-1500 on CF. What difficulty range would be the equivalent on Timus? Thanks

I want this to be the most down voted post on Cf. So I will say something offensive to make you mad. Programming sux!