How to get 6000 coins in LeetCode?

So, I'm curious, how exactly does one go about accumulating 6000 coins on LeetCode? Is it purely through solving problems and challenges, or are there other avenues to increase one's coin balance? Do the difficulty levels of the problems factor into the coin rewards? And if so, what's the optimal strategy for maximizing coin earnings? Lastly, are there any tips or tricks that experienced users can share to help speed up the process of reaching that 6000 coin milestone?