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Last active May 14, 2018

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# Day Four in Node for fun
# http://adventofcode.com/2017/day/4/
require! "fs"
require! 'prelude-ls': {lines, words, zip, map, filter, unique}
length = (.length)
sort = (.split('').sort().join(''))
input = map words, lines (fs.read-file-sync "input.txt", 'utf-8')
sorted = map ((x) -> map ((y) -> sort y), x), input
zippers = zip (map length, sorted), (map length, map unique, sorted)
console.log (length (filter ((x) -> x[0] is x[1]), zippers))
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sphvn commented May 14, 2018

--- Day 4: High-Entropy Passphrases ---
A new system policy has been put in place that requires all accounts to use a passphrase instead of simply a password. A passphrase consists of a series of words (lowercase letters) separated by spaces.

To ensure security, a valid passphrase must contain no duplicate words.

For example:

aa bb cc dd ee is valid.
aa bb cc dd aa is not valid - the word aa appears more than once.
aa bb cc dd aaa is valid - aa and aaa count as different words.
The system's full passphrase list is available as your puzzle input. How many passphrases are valid?

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sphvn commented May 14, 2018

--- Part Two ---
For added security, yet another system policy has been put in place. Now, a valid passphrase must contain no two words that are anagrams of each other - that is, a passphrase is invalid if any word's letters can be rearranged to form any other word in the passphrase.

For example:

abcde fghij is a valid passphrase.
abcde xyz ecdab is not valid - the letters from the third word can be rearranged to form the first word.
a ab abc abd abf abj is a valid passphrase, because all letters need to be used when forming another word.
iiii oiii ooii oooi oooo is valid.
oiii ioii iioi iiio is not valid - any of these words can be rearranged to form any other word.
Under this new system policy, how many passphrases are valid?

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