Codeforces Round 685 Screencast + Solutions (A-E2)

Описание: Contest link: https://codeforces.com/contest/1451
My submissions: https://codeforces.com/submissions/ga...

So this didn't go great because of not being able to clutch E2, but I'm very convinced that my solution is right, so I went over it anyway. We'll see when I can submit again, I guess.

Update on E2: so my solution in the video worked ( https://codeforces.com/contest/1451/s... ). But it turns out I definitely overcomplicated the solution in the video. With ALL the numbers from 0 to n - 1, there will always exist two indices i, j such that a[0] XOR a[i] == 1 and a[0] XOR a[j] is even. So the implementation can be much simpler, just directly using the queried XORs with the first element.

Timestamps:
Intro 00:00
A (solving) 00:53
B (solving) 05:11
C (solving) 09:18
D (solving) 15:08
E1 (solving) 39:01
Intermission 46:49
E1 (continuing) 51:27
E2 (solving) 1:11:32
E2 (trying to code fast) 1:58:47
Intermission (2) 2:16:28
A (solution) 2:19:27
B (solution) 2:22:47
C (solution) 2:25:49
D (solution) 2:32:29
E1/E2 (solution) 2:43:40
Nothing 2:55:05