We will hold AtCoder Regular Contest 162.
- Contest URL: https://atcoder.jp/contests/arc162
- Start Time: http://www.timeanddate.com/worldclock/fixedtime.html?iso=20230618T2100&p1=248
- Duration: 120 minutes
- Number of Tasks: 6
- Writer: tatyam, nok0
- Tester: maspy
- Rated range: — 2799
The point values will be 300-500-500-700-700-900.
We are looking forward to your participation!
Why some arc have discussions on codeforces but some don't?
Long time no see, ARC.
Nice problems with small $$$N$$$ s.
Interesting and tricky problems!
Actually, C can be solved in $$$O(n)$$$.
Screencast with commentary
how？Could you tell me?
I did. If you didn't notice, there is a link to screencast with commentary, where I'm explaining $$$O(n)$$$ solution to C, among other things.
emmmm.....I just thought you can solve the "subtree mex" in O(n)....
Well I know the O(n) solution for THIS porblem.
Anyway thank you!
emmmm.....I just thought you can solve the "subtree mex" in O(n)....
Well I know the O(n) solution for THIS porblem.
Anyway thank you!
I solved A by counting inversions in $$$O(n$$$ $$$log$$$ $$$n)$$$. The idea is creating a new array $$$cnt$$$ where $$$cnt_i$$$ is the number of $$$j$$$ so that $$$i < j$$$ and $$$a_i > a_j$$$. Then the answer is the number of minimum elements in array $$$cnt$$$. However I can't quite explain why it worked.
For problem B I just try to move the number $$$n$$$ to position $$$n$$$, $$$n-1$$$ to position $$$n-1$$$. When you are down to $$$1$$$ and $$$2$$$, if $$$2$$$ is in front of $$$1$$$, the answer is $$$No$$$. The answer is $$$Yes$$$ otherwise.
hey, can you send me the solution of B !!
Here. Can you see it?
Actrually,I didn't understand problem A's statement even when I passed the problem.
I just guessed what it may wish me to do.