Hey there! Here are the hacking statistics from Codeforces Round 283 (Div. 2).
It wasn't very good round for hackers (especially because of strong pretests), but still — let's take a quick look. (Hacks description will be added later, sorry).
Previous posts can be found here, including div. 1.
Stats
| Problem | Successful hacks | Unsuccessful hacks | Other* | Sum | Solutions which can be hacked | Accepted solutions | All solutions on final tests | Hackers efficiency** |
|---|---|---|---|---|---|---|---|---|
| 496A - Minimum Difficulty | 0 (0.00%) | 27 (55.10%) | 22 (44.90%) | 49 | 18 (0.81%) | 2193 (99.19%) | 2211 | 0.00% |
| 496B - Secret Combination | 3 (8.57%) | 19 (54.29%) | 13 (37.14%) | 35 | 78 (6.67%) | 1091 (93.33%) | 1169 | 3.70% |
| 496C - Removing Columns | 5 (11.90%) | 28 (66.67%) | 9 (21.43%) | 42 | 274 (29.37%) | 659 (70.63%) | 933 | 1.79 % |
| 496D - Tennis Game | 1 (33.33%) | 1 (33.33%) | 1 (33.33%) | 3 | 25 (43.10%) | 33 (56.90%) | 58 | 3.85% |
| 496E - Distributing Parts | 0 | 0 | 0 | 0 | 0 (0.00%) | 7 (100.00%) | 7 |
* one of the: INVALID_INPUT, GENERATOR_INCOMPILABLE, GENERATOR_CRASHED, IGNORED, OTHER.
** suggested by marat.snowbear and Yura_Sultonov — hacked solutions / (hacked solutions + solutions which failed on final tests).
I wondered why there were so many "Other" hacks, looking at them, it appeared that many of them were simply Invalid Input. Happily for these people it didn't count as (-50) points :)
Hacks and possible hacks description
496A - Minimum Difficulty
496B - Secret Combination
496C - Removing Columns
496D - Tennis Game
496E - Distributing Parts
Fastest hackers
| Problem | Time | Hacker | Defender | Hack |
|---|---|---|---|---|
| 496B - Secret Combination | 1:28:16 | Shahzodbek | Chaves | 129950 |
| 496C - Removing Columns | 0:54:36 | vishwacs111 | mkisic | 129848 |
| 496D - Tennis Game | 1:47:13 | ChoeWonHyok | voidmax | 130035 |
Because of lack of hacks overall, we listed below everybody with positive score ;)
Best hackers
| Hacker | Stats | Successful hacks | Unsuccessful hacks |
|---|---|---|---|
| vishwacs111 | +2-1 (150) | C: 129848 129851 | C: 129845 |
| Pifagorka | +1-0 (100) | B: 130019 | |
| Karnah | +1-0 (100) | C: 129909 | |
| Shahzodbek | +1-1 (50) | B: 129950 | A: 129843 |
| ChoeWonHyok | +1-1 (50) | D: 130035 | D: 130028 |
| bunos | +1-1 (50) | C: 130015 | C: 130068 |
Best rooms
| Room | #hacks | Hackers |
|---|---|---|
| 8 | 3 | vishwacs111 [2], AkshajK [1] |
| 35 | 1 | Shavkat_Aminov [1] |
| 84 | 1 | ChoeWonHyok [1] |
| 7 | 1 | Shahzodbek [1] |
| 39 | 1 | Karnah [1] |
| 61 | 1 | Pifagorka [1] |
| 15 | 1 | bunos [1] |
Best countries
| Country | #hacks | Hackers |
|---|---|---|
 India | 2 | vishwacs111 [2] |
 Uzbekistan | 2 | Shahzodbek [1], Shavkat_Aminov [1] |
 Russia | 2 | bunos [1], Karnah [1] |
 United States (USA) | 1 | AkshajK [1] |
I think this contest wasn't good for hacking... It wasn't an standard contest :(