--- title: each_cons, find_index - Advent of Code 2022 - Day 6 with Ruby slug: each_cons-find_index-advent-of-code-2022-day-6-with-ruby published_at: 2022-12-06 18:00:08 +0000 updated_at: 2026-03-04 20:15:09 +0000 summary: description: each_cons, find_index - Advent of Code 2022 - Day 6 with Ruby Challenge: https://adventofcode.com/2022/day/6 Solution: https://gist.github.com/cjavdev/98c558e5423f3bba42f15cedcefcd08e #ruby #adventofcode tags: [cjav_dev, web development tutorials, web development for beginners, vim, ruby, advent of code, aoc, advent of code 2022, advent of code 2022 day 6, advent of code day 6, advent of code ruby, advent of code solution, ruby solution, ruby solutions, ruby tutorial, ruby programming, ruby for beginners, ruby each_cons, each_cons, find_index, find_index ruby, ruby find_index, set, sets, ruby sets, ruby set] views: 256 author: CJ Avilla url: https://www.cjav.dev/videos/each_cons-find_index-advent-of-code-2022-day-6-with-ruby youtube_url: https://www.youtube.com/watch?v=W1d-yFjnI1I youtube_id: W1d-yFjnI1I embed_url: https://www.youtube.com/embed/W1d-yFjnI1I thumbnail_url: https://i.ytimg.com/vi/W1d-yFjnI1I/hqdefault.jpg type: video --- # each_cons, find_index - Advent of Code 2022 - Day 6 with Ruby *Published: December 06, 2022* *Views: 256* ## Watch [Watch on YouTube](https://www.youtube.com/watch?v=W1d-yFjnI1I) [![each_cons, find_index - Advent of Code 2022 - Day 6 with Ruby](https://i.ytimg.com/vi/W1d-yFjnI1I/hqdefault.jpg)](https://www.youtube.com/watch?v=W1d-yFjnI1I) ## Description each_cons, find_index - Advent of Code 2022 - Day 6 with Ruby Challenge: https://adventofcode.com/2022/day/6 Solution: https://gist.github.com/cjavdev/98c558e5423f3bba42f15cedcefcd08e #ruby #adventofcode ## Transcript what's up welcome back in this episode you'll see how to solve day six of the Advent of code 2022 with Ruby this one is called tuning trouble and the idea is that the elves are going to give you some communication device and you need to figure out how that device is going to communicate and it's supposed to be like broken and so we're going to look at some raw data stream buffers and then try to determine when sort of the start of a packet start or like where the in the Stream of information the packet is actually starting so we're going to get a bunch of strings there or our input is going to be one super long string and our goal is to figure out where there are four consecutive letters that are unique and so if we look at this first example we have mjq and then J repeats so the first four characters are not unique because we have J repeating and then after that we have j p q and so Q is now repeating and then we have an M again so this is the first time that we see four unique letters is j p q m so the start of this packet we would say is like seven because it's the four characters that are unique plus whatever buffer was in the beginning so we're given some examples here with telling us where the first marker is happening and what we need to do is figure out based on some really long inputs this is going to be our input it's just one ginormous cons like a string of characters and so the first thing we want to do is open up day six so we're going to say okay and here we'll say require R spec auto run and we want to our spec dot describe we'll just say this is for day six and we're gonna say it works for the example cases all right so what we want to do is expect that marker for this thing is going to equal the number five okay we can do it let's do it for just a couple of these examples we'll grab this one and say okay we want this use case also and now we should be able to just run this so we're going to jump over here and say Ruby day six day six and we have a failing test good undefined method marker let's go make our marker method and that's going to take some input and if we run our test again now we're going to have some unexpected we expected five but we got nil okay so what we want to do is we want to split up our input into characters and then we need to figure out where the first four consecutive characters are unique and so the way I think we can do this is say like input dot chars that'll give us all the characters dot each cons so each consecutive four so each cons is an innumerable method that will give you each consecutive group so if we look at each cons here this is a handy method so if we say if we look at the range from one to five and we have each consecutive then you'll notice that we're going to get the first one two three then we see two three four then we see three four five and that's exactly what we want to do we want to inspect each four consecutive groups and for each of those we want to see if they are unique so what we can do is take each of the arrays that are going to be yielded by each cons and we can map those into a set so again we're going to require the set class or the set Gem and now that we have sets let's actually look at what we get back here so we're going to have several sets so the first one bvw is is only showing us bvw as a set because when we're talking about a set requires that its elements are all unique so if we take the first four characters from this string here bvwb and we convert it into a set we're only going to have bvw because B appears twice and a set can only have unique unique values so now what we can do is we can look at the length of the set and if the length is not equal to four then we know that this set has some repeating values in it then when we look at the next set we'll notice that it has four and so what we need to do is figure out okay if we get to the second set in the list and it has four then we need to add four plus one for the first character of the character sequence so here what we can do is we can say find index so we want to find the index where the sets size is equal to four and that should give us back in this case it should give us back two or I guess we add one because zero um it's zero indexed okay so then we want to take that and we want to add to it the number four okay so if we run this again now we have a passing test fantastic all right so let's grab all of our input and just at the bottom here we can just call P marker with our input and then run our Ruby code again and our output is here we also have the tests running but 1142 if we come back over here and search for 1142 that is the answer for part one so that is the solution for part one now in part two it says your device's communication system is correctly detecting packets but it still isn't working it looks like it needs also to do messages so messages start with 14 distinct characters instead of four so it's the same exact solution here but the only difference is that we want to use 14 instead of four so what I'm going to do is take in a length argument here and so we want chunks that are that length in our example tests here we can pass in four and our this should still continue working and then we also need to check that the set size when we're finding the index of the correctly unique 14 character set is also going to have the same length and then we also need to add the same sort of length or offset so those markers are going to continue to work and then there's some other examples for part two so we can expect that this marker in part two given 14 is going to equal 19. so let's run this again and oh marker now we have to change this one to be 14. and if we run it again okay we have our tests are passing and we get the answer is 2803 if we search the puzzle answer was 2803 awesome so that is the solution for day six couple of cool things here each cons if you haven't already seen it go check it out and then find index is just going to detect and return When when the Block matches as it's iterating over the indices so that's helpful and handy if you're curious again like I would just crack open IRB and play around with a is I don't know like one two three four five and then you can say like Ada each cons 2.2a and so that'll give you like okay that's the first two and then two three that's the second two and then three four that's the third group of two the third pair you can play around with this each cons idea it's it's a it's actually like a pretty useful method here right like you can slice things up in a few different ways and it lets you look at like a sliding range of values that's it for today thanks so much for watching really appreciate your time and attention and we'll see you next time --- [Back to all videos](https://www.cjav.dev/videos) --- ## Hey Agent, thanks for visiting! 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