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Colin Fay
Colin Fay

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Advent of Code 2020-02 with R & JavaScript

#rstats #adventofcode #javascript

Solving Advent of Code 2020-01 with R and JavaScript.

[Disclaimer] Obviously, this post contains a big spoiler about Advent of Code.

[Disclaimer bis] I’m no JavaScript expert so this might not be the perfect solution. TBH, that’s also the case for the R solution.

About the JavaScript code

The JavaScript code has been written in the same RMarkdown as the R code. It runs thanks to the {bubble} package:https://github.com/ColinFay/bubble

Instructions

Step 1

  • Inputs are of the form 1-3 a: abcde, for min-maxletter:code, where letter must be found at least min and no more than max in code

How to: split the input in four columns, for min,max,letter, andcode, count the number of letter in code, and then make sure this count is >= min and <= max.

Step 2

  • Inputs are of the form 1-3 a: abcde, for position1 position2 letter:code, where code[position1] == letter | code[position2] == letter but not code[position1] == letter & code[position2] == letter, nor !code[position1] == letter & !code[position2] == letter

Find the complete instructions at:https://adventofcode.com/2020/day/2.

R solution

Part one 

# Read ipt <- read.delim( "2020-02-aoc.txt", header = FALSE ) library(dplyr, warn.conflicts = FALSE) library(tidyr) library(purrr) ipt %>% # Create the four columns separate(V1, c("min", "max", "letter", "code")) %>% pmap_dbl(~{ # If the letter is not in the input, return 0 if (!stringr::str_detect(..4, ..3)) return(0) # Count the n of letter in code count <- stringr::str_count(..4, ..3) # Is this count between the boundaries? count >= as.numeric(..1) & count <= as.numeric(..2) }) %>% sum() ## [1] 607
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Part two 

ipt %>% # Create the four columns separate(V1, c("min", "max", "letter", "code")) %>% pmap_dbl(~{ #browser() # Split the code  code <- strsplit(..4, "")[[1]] # code[position1] == letter p1_match <- code[as.numeric(..1)] == ..3 # code[position1] == letter p2_match <- code[as.numeric(..2)] == ..3 # No match if (!p1_match & !p2_match) return(0) # Two matches if (p1_match && p2_match) return(0) return(1) }) %>% sum() ## [1] 321
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JS solution

Part one & Two

// Reading the file and converting it to int

const fs = require('fs') var ipt = fs.readFileSync("2020-02-aoc.txt", 'utf8').split("\n").filter(x => x.length != 0); ipt = ipt.map(x => x.split(/[^A-Za-z0-9]/));
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// Doing the combn

var res1 = ipt.map(x => { if (!x[4].includes(x[2])) return 0 var match = x[4].match(new RegExp(x[2], "g")).length return match >= parseInt(x[0]) & match <= parseInt(x[1]) })
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// Solution

// https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Array/reduce const reducer = (accumulator, currentValue) => accumulator + currentValue; res1.reduce(reducer) ## undefined ## undefined ## 607
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// Part 2

var res2 = ipt.map(x => { // Split the code  var code = x[4].split("") // code[position1] == letter var p1_match = code[parseInt(x[0]) - 1] === x[2] // code[position1] == letter var p2_match = code[parseInt(x[1]) - 1] === x[2] // No match if (!p1_match && !p2_match) return 0 // Two matches if (p1_match && p2_match) return 0 return 1 })
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// Solution

res2.reduce(reducer) ## 321
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