mshenfield / admissions-challenge

Admissions Challenge 1 of 2

This is the first of two Admissions Challenges for MakerSquare. This will allow you to showcase your knowledge of basic JavaScript. The next challenge will be more advanced; we will present it to you after your "Admissions Q&A Interview".

To get started, create a file called mks-admissions-challenge-1.js. In this file you will write your solutions. All answers should be in the same file, separated by comments.

When you're finished...

Submit it here.

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Challenge: Passing around notes in class

In this challenge you will write be decoding secret messages using JavaScript. You will write a function decrypt that will receive a string and return a decrypted string:

var decryptA = function(message) {
  // Your code goes here.
  // You will process the incoming message and return the decrypted message
};

Read on to Phase 1 for the challenge requirements. If you have trouble solving this, you should review Codecademy and our public JS Intro course.

Phase 1

Your task is to decrypt the true meaning of a given sentence. Here's an example:

laugh ride lol hall bozo

On first glance, this seems like an odd sentence. However, there's a secret message hidden beneath. If you combine the last letter of each word, you will find the sensible message "hello".

Complete the decryptA function so that it decrypts messages like this one. Here are some examples:

var decryptA = function(message) {
  // Your code here
}

var result1 = decryptA("laugh ride lol hall bozo")
console.log(result1) // This should be "hello"

var result2 = decryptA("dog polo boo sudd noob smiley ride")
console.log(result2) // This should be "goodbye"

Phase 2

We've been exposed! Our encryption technique was way too easy to figure out, and was thus discovered... it's time to change it up.

Here's the new encryption scheme:

• Just like before, a single letter is taken from each word in the sentence.
• Unlike before, either the first or last letter is taken.
• The letter taken is decided by which of the first or last is "greater" (e.g. "b" > "a", "c" > "b", etc.)

Here are some examples based on the above rules:

"hello" translates to "o" because "o" is greater than "h". "goodbye" translates to "g" because "g" is greater than "e".

Full sentence example:

wazdee apple love bic nooo more end

This sentence will decrypt to "welcome".

Complete the decryptB function so that it decrypts messages with the new scheme. Here are some examples:

var decryptB = function(message) {
  // Your code here
}
var result1 = decryptB("wazdee apple love bic nooo more end")
console.log(result1) // This should be "welcome"

var result2 = decryptB("bria loud fuzu antidote")
console.log(result2) // This should be "blue"

Hint: you can compare letters in JS: "c" > "b"

Phase 3 - Extra Credit

This phase is not required. You should schedule an interview before you attempt this.

We keep getting hacked! Looking at the first and last letter is not effective enough - we need a new structure. Here's the new encryption scheme:

• Starting with n=1, for each word n, take the nth letter of that word.
  • For example, take the 1st letter of the 1st word, 2nd letter of the 2nd word, 3rd letter of the 3rd word, etc.
• If a word has length len such that n > len, then continue consuming words until you reach letter n.
• Skip over any words consumed in the manner of the previous rule.

This is much more complicated than the previous schemes. Here are some examples:

• The message oh i understand banter decrypts to out - since the second word needs a second letter, it continues into the next word's letters to find it. In this case it steps 1 letter into the next word.
• The message a ob ooc dd oeoo ooooof decrypts to abcef - since the fourth word needs a fourth letter, it continues into the next word's letters to find it. In this case it steps 2 letters into the next word.
• The message a b c decrypts to ac - since the second word needs a second letter, it continues into the next word's letters to find it. Afterwards, because c is already consumed, there are no more words to continue with.
• The message a b c d e f decrypts to acf - both words b and d need to step into their next words in order to get their letters.

Write a decryptC function so that it decrypts messages with this new scheme.

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Coding Challenge Part 2

Submit a completed version of this first challenge to access the next one. You'll be given the link to the second challenge automatically upon submission of this challenge.