### Le_Gusto's blog

By Le_Gusto, history, 2 months ago,

After a busy weekend rowing abroad, it was finally time to get back to coding. By skipping one of my lectures on heaps, I managed to make it back home and join the contest only 20 minutes late, ready to solve some easy problems.

The contest went way worse than I expected — I only solved A and B. It might just be coping, but I think problems C and D were too difficult for Div. 4 — they felt Div. 3 level at the very least. I spent a good while trying to find some patterns on C, but couldn't manage to put together a solution. For problem D, I didn't notice very important key details and spent considerable time researching how to use bitsets, but even after I figured out how to read the bits of numbers, the solution I had didn't work and would probably have been too slow anyway. While doing problem E, I made a mistake when I came up with my algorithm to solve it, which turned out to be a major flaw that made the whole algorithm useless. It's a bit sad that I will most likely drop down below 1k, but I'll just climb back up.

I think that I'll do some problems on Leetcode involving bits to better prepare for questions like D. I'll also check out the editorials and try to find how I could come up with solutions for C and E once they get published.

'til the next contest!

• +8

 » 2 months ago, # |   0 same. mine was also an onsite contest so I panicked even more :(
•  » » 2 months ago, # ^ |   0 I solve only 4 problems (A-D). It's not bad, but I wanted to solve all the problems or all except the last one (F in this contest). I think that last Div.3 and this Div.4 were difficult
 » 2 months ago, # | ← Rev. 2 →   0 C is a simple problem. Just pre calculate the answer for each possible value. D is a bit tricky, we need to observe one simple thing that a group can have at max 2 element when x ^ y = (1<<31-1) which is all ones. We can use two sum to solve this kind of problems.
•  » » 2 months ago, # ^ |   0 two sum??
•  » » » 2 months ago, # ^ |   0 Two sum pattern. Sorry! You just need to find the pairs which can be clubbed together. By storing in a map.
•  » » » » 2 months ago, # ^ |   0 ok thanks
 » 4 weeks ago, # |   0 i solved A,B,C. C was a pre-compute one. i gave the recent round 935 div3. and it was horrible experience. i solved 0 problems getting WA in A. will i get any rating change?