MBLTdev online quest: prizes and answers
Hi, Habr! On Wednesday, we wrote down a quest , and judging by the flow of comments and messages, you liked the quest and made you think hard. We are glad! In this post we summarize: we will reveal the correct answers and present the prizes.
Today the prizes went to the winners, check your mail.
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Now we will tell you how to solve the tasks. Under the cut - the answers.
Task: on the promotional video you need to see a link to the quiz.
Solution: you need a keen eye and a slow view function on YouTube. We get the coveted link.
Task: to decipher the text.
Solution: the listing is presented, perhaps, in the most popular esoteric language - Brainfuck . To solve it, it was enough to find the language interpreter and get the answer: Mobile app developers love the MBLTdev.
Task: there are two hashes on the screen, you need to find the third one.
Solution: by trial and error, we determine that sha1 is used, and we get the answer: f5fbaef89c6a66b135a5e00947a45932d9f1e8a6.
The third level (we know, he especially
Task: cipher text is presented. We did not ask to decipher the phrase. It was necessary to give an answer what is encrypted. The answer must also be in the format of the source cipher.
Solution: Suppose that the text is encrypted with "Caesar's cipher". When the alphabet is shifted 17 points to the right, we will find the source text:
= "Functions that use the base type should be able to use subtypes of the base type without knowing it." This is the principle of substitution by Barbara Liskov. Many tried to enter the decrypted text, the name of the principle in different languages, an abbreviation, but in response only received:
Let's try to follow the principle:
To do this, we determine the magnitude of the shift of the alphabet in the original phrase:
On the 16th position we find the original text, therefore we encrypt the phrase “Barbara Liskov's substitution principle” with the 16th offset: Jaasheyosya Iiubvpėyus Rparpak Yshbyus. Also valid are the answers of Barbara Liskov and Liskov - Rparpap Yshbyus and Yshbyus respectively.
Task: specify the coordinates.
Solution: In quizzes of this kind, a common task is the question of coordinates. The clue is the mask after nay: and nrbi:
Need to understand what nay and nrbi mean? Everything is simple and difficult at the same time: giving an explicit hint for lat and long would be too obvious, so we wrote these frequent expressions with the Dvorak layout.
Coordinates were considered with an error and it was enough to enter at least 4 decimal places. The correct answer is 55.7407, 37.6090.
The answer is in the picture. Literally. You need to open the picture in any text editor:
Agree, it was fun. And at MBLTdev, 2017 will be even more fun: useful reports and dating + Codelabs and quizzes for iOS and Android developers with cool gifts. See you October 27th! Sign up today.
Statistics
Prizes
Today the prizes went to the winners, check your mail.
')
- Annual subscriptions to JetBrains products were received by Insaf, Michael and Daniel.
- MBLTdev 2017 Mobile Developer Conference Conference Tickets - Alexey Laguta, Mikhail and Artem.
- T-shirts MBLTdev 2017 - Ustinov Valery, Ruslan Akhtyamov and Pavel Kamaev.
- A 20% discount on tickets for MBLTdev 2017 - our gift to everyone who completed the quest to the end.
Now we will tell you how to solve the tasks. Under the cut - the answers.
Log in to the quest
Task: on the promotional video you need to see a link to the quiz.
Solution: you need a keen eye and a slow view function on YouTube. We get the coveted link.
First level
Task: to decipher the text.
Solution: the listing is presented, perhaps, in the most popular esoteric language - Brainfuck . To solve it, it was enough to find the language interpreter and get the answer: Mobile app developers love the MBLTdev.
Second level
Task: there are two hashes on the screen, you need to find the third one.
Solution: by trial and error, we determine that sha1 is used, and we get the answer: f5fbaef89c6a66b135a5e00947a45932d9f1e8a6.
The third level (we know, he especially made you laugh amused)
Task: cipher text is presented. We did not ask to decipher the phrase. It was necessary to give an answer what is encrypted. The answer must also be in the format of the source cipher.
Solution: Suppose that the text is encrypted with "Caesar's cipher". When the alphabet is shifted 17 points to the right, we will find the source text:
= "Functions that use the base type should be able to use subtypes of the base type without knowing it." This is the principle of substitution by Barbara Liskov. Many tried to enter the decrypted text, the name of the principle in different languages, an abbreviation, but in response only received:
Let's try to follow the principle:
To do this, we determine the magnitude of the shift of the alphabet in the original phrase:
On the 16th position we find the original text, therefore we encrypt the phrase “Barbara Liskov's substitution principle” with the 16th offset: Jaasheyosya Iiubvpėyus Rparpak Yshbyus. Also valid are the answers of Barbara Liskov and Liskov - Rparpap Yshbyus and Yshbyus respectively.
Fourth level
Task: specify the coordinates.
Solution: In quizzes of this kind, a common task is the question of coordinates. The clue is the mask after nay: and nrbi:
Need to understand what nay and nrbi mean? Everything is simple and difficult at the same time: giving an explicit hint for lat and long would be too obvious, so we wrote these frequent expressions with the Dvorak layout.
Coordinates were considered with an error and it was enough to enter at least 4 decimal places. The correct answer is 55.7407, 37.6090.
Fifth level
The answer is in the picture. Literally. You need to open the picture in any text editor:
Agree, it was fun. And at MBLTdev, 2017 will be even more fun: useful reports and dating + Codelabs and quizzes for iOS and Android developers with cool gifts. See you October 27th! Sign up today.
Source: https://habr.com/ru/post/339668/
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