Can anyone suggest some basic DP problems (must be on Codeforces) for me to solve? I want to have a try.

Before round, $$$6$$$ tests.

After round, $$$365$$$ tests.

Added $$$359$$$ tests...

Is there a change greater than this?

I found that one can hack himself in Educational Rounds. What will happen if the hack is successful? I wonder because I'm not bery experienced in it. Please comment if you know.

What is Div.1+Div.2? Is it a round to choose from Div.1 and Div.2 or a round with difficulty Div.2A to Div.1F? I have rating $$$675$$$ and contribution $$$-103$$$. Can I take part in this round? Also, is hack avaliable?