And statistics from Codeforces Round 284 (Div. 2) (this round should be named after dreamoon_love_AA).
Previous posts can be found here, including post for div. 1.
Stats
We had only 21 successful hacks for this round (pretests were pretty good).
| Problem | Successful hacks | Unsuccessful hacks | Other* | Sum | Solutions which can be hacked | Accepted solutions | All solutions on final tests | Hackers efficiency** |
|---|---|---|---|---|---|---|---|---|
| 499A - Watching a movie | 13 (18.06%) | 39 (54.17%) | 20 (27.78%) | 72 | 108 (5.03%) | 2041 (94.97%) | 2149 | 10.74% |
| 499B - Lecture | 2 (2.47%) | 15 (18.52%) | 64 (79.01%) | 81 | 3 (0.14%) | 2118 (99.86%) | 2121 | 40.00% |
| 499C - Crazy Town | 6 (11.54%) | 40 (76.92%) | 6 (11.54%) | 52 | 156 (20.29%) | 613 (79.71%) | 769 | 3.70% |
| 499D - Name That Tune | 0 | 0 | 0 | 0 | 9 (75.00%) | 3 (25.00%) | 12 | 0.00% |
| 499E - Array and Operations | 0 | 0 | 0 | 0 | 18 (64.29%) | 10 (35.71%) | 28 | 0.00% |
*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).
Hacks and possible hacks description
499A - Watching a movie
499B - Lecture
Here we have only some implementation issues. Pretests covered nearly everything.
499C - Crazy Town
TBD (if someone is willing to share your hacks/mistakes for this problem, I would be really happy :))
499D - Name That Tune
Many solutions with even correct complexity 
get TLE. The reason might be that there could be many clever solutions with 
complexity, which some tricky breaks and author wanted to fail them — that's might the reason for tight limits.
499E - Array and Operations
Fastest hackers
| Problem | Time | Hacker | Defender | Hack |
|---|---|---|---|---|
| 499A - Watching a movie | 0:48:55 | divij_nsit | Dmitriy_M | 130181 |
| 499B - Lecture | 1:41:16 | amit43 | gupta_shvm | 130307 |
| 499C - Crazy Town | 0:51:35 | minimario | progra | 130189 |
Best hackers
| Hacker | Stats | Successful hacks | Unsuccessful hacks |
|---|---|---|---|
| sorry_dreamoon | +2-0 (200) | C: 130237 130268 | |
| Nozim | +2-1 (150) | A: 130264 B: 130419 | A: 130258 |
| amit43 | +1-0 (100) | B: 130307 | |
| divij_nsit | +1-0 (100) | A: 130181 | |
| heavenly_phoenix | +1-0 (100) | A: 130206 | |
| minimario | +1-0 (100) | C: 130189 | |
| gauravanand25 | +1-0 (100) | C: 130349 | |
| ndatta | +1-0 (100) | A: 130395 | |
| ziad.mohamed | +1-0 (100) | A: 130247 | |
| 404Error | +1-0 (100) | A: 130280 | |
| bes4etnov | +1-0 (100) | A: 130199 | |
| grayhathacker | +1-0 (100) | C: 130300 | |
| icecode | +1-0 (100) | A: 130430 | |
| progra | +1-0 (100) | A: 130308 | |
| v2v4 | +1-0 (100) | A: 130225 | |
| ZzZZzzzZZZZZzzzzzzzz | +1-1 (50) | A: 130208 | A: 130283 |
| SlaMandor | +1-1 (50) | C: 130352 | C: 130321 |
| mbaros | +1-2 (0) | A: 130303 | A: 130401 C: 130216 |
| buzden | +1-2 (0) | A: 130413 | C: 130345 130365 |
Best rooms
| Room | #hacks | Hackers |
|---|---|---|
| 27 | 3 | minimario [1], progra [1], buzden [1] |
| 96 | 2 | SlaMandor [1], mbaros [1] |
| 65 | 2 | Nozim [2] |
| 22 | 2 | sorry_dreamoon [2] |
| 2 | 1 | v2v4 [1] |
| 67 | 1 | 404Error [1] |
| 54 | 1 | gauravanand25 [1] |
| 97 | 1 | amit43 [1] |
| 47 | 1 | grayhathacker [1] |
| 80 | 1 | heavenly_phoenix [1] |
| 50 | 1 | divij_nsit [1] |
| 83 | 1 | ZzZZzzzZZZZZzzzzzzzz [1] |
| 52 | 1 | ziad.mohamed [1] |
| 55 | 1 | ndatta [1] |
| 58 | 1 | bes4etnov [1] |
| 29 | 1 | icecode [1] |
Best countries
| Country | #hacks | Hackers |
|---|---|---|
 India | 6 | gauravanand25 [1], amit43 [1], v2v4 [1], divij_nsit [1], icecode [1], grayhathacker [1] |
 Russia | 2 | bes4etnov [1], buzden [1] |
 Tajikistan | 2 | Nozim [2] |
 Kazakhstan | 1 | ZzZZzzzZZZZZzzzzzzzz [1] |
 Bangladesh | 1 | ndatta [1] |
 Egypt | 1 | ziad.mohamed [1] |
 Armenia | 1 | mbaros [1] |
 United States (USA) | 1 | minimario [1] |
just look at successful hacks...
I think this contest wasn't standard...
With easy problems or strong present tests...
It's so good that some one with 5 month of registration allows himself/herself to say a contest was standard or not :). and the other thing is he says the Problems were easy while he/her solved just A & B and he couldn't solve C in 100 minutes. and I am looking at successful hacks and I just can't get anything else different than the ones already said by kostka.