---
title: Percent delimiters %w, zip - Day 06 - Advent of Code 2023
slug: percent-delimiters-w-zip-day-06-advent-of-code-2023
published_at: 2023-12-06 17:00:14 +0000
updated_at: 2026-03-04 20:15:17 +0000
summary: 
description: See how to solve the Day 6 \&quot;Race\&quot; puzzle for the advent of code with Ruby! We’ll determine how long to press a boat&#39;s speed button to beat distance records. We’ll talk about Ruby&#39;s %w delimiter to extract race times and distances. Then use `zip` to combine the time and distance arrays together.  We’ll increment a counter when the distance beats the record. By reducing these counters per race, we can find the final product.   While this approach works, faster alternative solutions are using the quadratic formula for a mathematical model or counting below threshold distances. This allows skipping unnecessary iterations.  Advent of Code: https://adventofcode.com/ My Solutions: https://gist.github.com/cjavdev/d15a2a4ffed6c840c2fb28a093e9f927/ Playlist https://www.youtube.com/playlist?list=PLS6F722u-R6KYlGyUv65EFpGKl2Esmurr  #adventofcode  #ruby
tags: [cjav_dev, Learn to code, Beginner ruby, Advent of code, Advent of code 2023, Advent of code ruby, Aoc ruby, Aoc 2023, Vim, Advent of code vim, Advent of code explainer, Advent of code challenge, Code challenge, Advent of code tutorial, Web development tutorial]
views: 198
author: CJ Avilla
url: https://www.cjav.dev/videos/percent-delimiters-w-zip-day-06-advent-of-code-2023
youtube_url: https://www.youtube.com/watch?v=GBY_GZs3CZ8
youtube_id: GBY_GZs3CZ8
embed_url: https://www.youtube.com/embed/GBY_GZs3CZ8
thumbnail_url: https://i.ytimg.com/vi/GBY_GZs3CZ8/hqdefault.jpg
type: video
---

# Percent delimiters %w, zip - Day 06 - Advent of Code 2023

*Published: December 06, 2023*
*Views: 198*

## Watch

[Watch on YouTube](https://www.youtube.com/watch?v=GBY_GZs3CZ8)

[![Percent delimiters %w, zip - Day 06 - Advent of Code 2023](https://i.ytimg.com/vi/GBY_GZs3CZ8/hqdefault.jpg)](https://www.youtube.com/watch?v=GBY_GZs3CZ8)

## Description

See how to solve the Day 6 &quot;Race&quot; puzzle for the advent of code with Ruby! We’ll determine how long to press a boat&#39;s speed button to beat distance records. We’ll talk about Ruby&#39;s %w delimiter to extract race times and distances. Then use `zip` to combine the time and distance arrays together.

We’ll increment a counter when the distance beats the record. By reducing these counters per race, we can find the final product. 

While this approach works, faster alternative solutions are using the quadratic formula for a mathematical model or counting below threshold distances. This allows skipping unnecessary iterations.

Advent of Code: https://adventofcode.com/
My Solutions: https://gist.github.com/cjavdev/d15a2a4ffed6c840c2fb28a093e9f927/
Playlist https://www.youtube.com/playlist?list=PLS6F722u-R6KYlGyUv65EFpGKl2Esmurr

#adventofcode  #ruby

## Transcript

wait for it what&#39;s up welcome back in this episode you&#39;ll see how to solve day six for the Advent of code challenge in 2023 this one&#39;s called wait for it and in this scenario we have some races some boat races and the idea is that we have some some data from a boat race here and the document is going to describe how long the race lasts and the record distance for the race and our job is to figure out what we need to do with this toy boat to make it win the race and the way that the race is won is by holding down a button on the top of the boat for a certain number of seconds or milliseconds and depending on how long we hold down the button that will increase the speed of the boat and then we let go of the button and the boat travels some millimeter some distance if we hold the button down for a really long time it will go really fast but it will only be able to travel a short distance if we hold it down for too long in this case what we need to do is break up this seven to figure out if we hold it down for 1 second how far will it go or two seconds or 3 seconds or 7 Seconds If We Hold It Down for 7 Seconds it doesn&#39;t have any time to travel anywhere if we if we don&#39;t hold the button down at all it doesn&#39;t have any speed to travel anywhere so we need to find some Middle Ground where we&#39;re going to hold it down maybe for 3 or 4 seconds and that should get us to uh to travel 12 mm so if we hold down the button for 3 milliseconds then after 3 milliseconds the boat will be traveling at 3 mm/ second and then we can let go and then it will travel at 3 mm/s for 4 seconds and it will end up traveling 12 mm we&#39;ve got some input here and let&#39;s just play around with this and see if we can get this working okay so we&#39;re going to drop this in here rather than using a he do today I thought it might be fun to talk about percent delimiters in Ruby so we&#39;ve already got the spaces between the words here we can just change this D to match Ruby style and we can say percent W percent W will give us the words as an array so this is like another way of creating a list of words so if we print out time here and we run Ruby main. RB then we get 7 15 and 30 so that&#39;s like the words that are in this list separated by spaces now what we can do is just map this to I map that to I and we&#39;ll get back the numbers 7530 so now we have an array of times and we have an array of distances and what I&#39;ve been excited to use is the zip method so we can zip with distance and this is going to give us back some new array that has subarrays where each element is the element from the arrays that were being zipped together so they&#39;re we&#39;re combining all of the arrays zippering them together yeah zipper I guess it&#39;s going this way we&#39;re zippering the array elements together and we come up with this so now we have a list of race where the first element is the time and the second element is the record distance so now we&#39;ve got some races and what we want to do is iterate over those races and for each race we want the time and distance and then we want to figure out like what is the oh I guess like we got to figure out what our answer is here the what the answer that it&#39;s looking for in the first case is to count up the number of way that you can beat the record so if we look at holding down the button for 0 seconds holding down the button for 1 second holding down the button for two seconds all the way up to 7 seconds and then we want to see how far we can travel for each of those so if we do time. times. uh do I that will give us some number of seconds held or something the number of seconds we&#39;re holding down and if the number of seconds held so distance in this case so this is let&#39;s do this as like the record distance and we&#39;ll call our new instance or our new variable distance is equal to the number of seconds held that&#39;s going to be how long we&#39;ve held it down so that&#39;s our speed and now we need to multiply our speed by the time minus the number of seconds held right it&#39;s like the time remaining seconds held times time minus seconds held that should give us a distance I think so let&#39;s just print out time seconds held and distance and here we go so if we look at the first one seven and zero okay so on the right hand column here we have 0 6 10 12 12 6 and then over here we have as the answer for the distance traveled is 0 6 10 12 12 6 0 so this is like the far right column there is correct for distance so what we want to find out now is if the distance was greater than the record distance then we want to print out stuff right so if the distance was greater than the record so in the first case here we have 1 two 3 4 this is a uh an extra print at the bottom here so we have four occurrences where the distance was bigger then we have a bunch more occurrences then we have a bunch more so now what we want to do is the answer is the number of ways you can beat the record so if we multiply these values together you get 288 which is our answer for the first part so we need to figure out a count so if we do ways is zero and then we&#39;ll do ways plus equals 1 okay so that&#39;ll be the number of ways that we can win actually we can pull this out here I think right because we need the number of ways for the whole no yeah we need the number of ways for each race P ways right we need the number of ways and then we need to multiply these together so we need to collect these up somehow and then multiply so one way we can do this is we have some accumulator and we&#39;ll start that at one and then we could say ACC times equals ways and we&#39;ll print out ACC at the end and run this and we get 288 so that is the answer for the example input now let&#39;s grab the the real input we&#39;ll grab our puzzle input here which is similarly not bad and we&#39;ll just paste this in come over here make that t that D and per perent ww. map okay if we run it against our example input we get 44 035 blah blah blah for part one 440 3592 awesome that was our answer okay now let&#39;s see what part two says as the race is about to start you realize the piece of paper with the race times and Records is actually One race so the King was wrong so the king is like the space between the letters and what this is saying is oh there&#39;s actually just like no spaces between 7 one5 or seven and one and five and three so there&#39;s just one race and it has this huge time number so let&#39;s grab these again and let&#39;s just remove the spaces here I think this will work and we should just get an array oops okay so if we run this again all right 380 17587 380 17587 boom okay all right so that is the answer for part two so relatively straightforward this is fun using zip check that out that is one of the innumerable methods let&#39;s see if we can clean this up a little bit we&#39;ve got like this accumulator thing that&#39;s dangling around and we&#39;re printing that out at the end one way we could improve this is like move our accumul like the logic for accumulating all of these up into a reduce method and we can start our accumulator at one and then we can pass in the accumulator as the first argument to the block the second argument to the block is going to be the element yielded by the iterator and because before we were just getting an array we were able to implicitly destructure but now uh we have one argument that is going to be the accumulator and the second argument is going to be the array of time and record and so we need to use these parentheses to explicitly de construct that into the arguments so now I think what we can do is just return accumulator times ways and this should give us back some number result and then we&#39;ll P result and then we can remove the accumulator from the top and bottom and we get the same answer so that&#39;s cool now we&#39;ve got ways here there&#39;s likely some other things we can do seconds held times the time minus seconds held this distance can actually be just replaced inside of here we don&#39;t actually need to go that far it&#39;s worth noting there are solutions to this problem that use a Pure math solution so you can use the quadratic equation now one other thing that we could do is we could actually optimize this quite a bit right like right now we&#39;re counting up the ways we&#39;re iterating over all of the different potential seconds held but really we only need to go like the list is going to be something like 0 six 10 12 12 60 or something like this so we have this mountain where we&#39;re starting low we&#39;re going high and then we&#39;re going back down and we&#39;re going to have some slice that goes through the mountain so there&#39;s two points if we can find those two points then you just take the difference between those two and you get the the count of those that are in the middle but another way that we could improve this is we could count up um we could count up the number of uh ways that are below the curve and then we could count up the number of ways that are below the curve on the other side and then combine those two subtract them from the total and get the answer so there&#39;s a few different ways to optimize this but I think this is like the this is the one in my opinion that reads the cleanest and since it works I&#39;m just going to keep it like this thanks so much for watching and we&#39;ll see you in the next one

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