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Advent of Code 2020-01 with R & JavaScript

colinfay profile image Colin Fay Originally published at colinfay.me on ・2 min read

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

[Disclaimer] Obviously, this post contains a big spoiler about Advent of Code, as it gives solutions for solving day 1.

[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

  • Combine all the possible duos and trios of the input numbers

  • Locate the combination that equals 2020

  • Multiply the numbers from this combination to get the puzzle answer

Find the complete instructions at:https://adventofcode.com/2020/day/1.

R solution

Part one

# Read
ipt <- read.delim( "2020-01-aoc.txt", header = FALSE )
library(dplyr, warn.conflicts = FALSE)
# Creating all the combinations
tidystringdist::tidy_comb_all(ipt$V1) %>%
  # Adding them together
  mutate(sum = V1 + V2) %>%
  # keeping only the one that equals 2020
  filter(sum == 2020) %>%
  # Multiplying it
  mutate(res = V1 * V2) %>%
  # Getting the answer
  pull(res)


## [1] 445536
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Part two

# Creating all the combinations
combn(
  ipt$V1, 
  3
) %>% 
  # Transposing the matrix and turning it to a tibble
  t() %>%
  as_tibble() %>%
  # Same old song as step 1
  mutate(sum = V1 + V2 + V3) %>%
  filter(sum == 2020) %>%
  mutate(res = V1 * V2 * V3) %>%
  pull(res)


## [1] 138688160
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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("2020-01-aoc.txt", 'utf8').split("\n").filter(x => x.length != 0);
ipt = ipt.map(x => parseInt(x));
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// Doing the combn

var ipt2 = ipt;
var comb = ipt.flatMap(i => ipt2.map(j => [i, j]))
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// Getting the 2020

var twentytwenty = comb.filter(x => (x[0] + x[1]) === 2020)
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// Solution

twentytwenty.reduce(y => y[0] * y[1])


## 445536
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// Same with three

var ipt3 = ipt;
var comb2 = ipt.flatMap(i => ipt2.flatMap(j => ipt3.map(k => [i, j, k])));
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// Doing the computation

var twentytwenty2 = comb2.filter(x => (x[0] + x[1] + x[2]) === 2020)
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// Solution

twentytwenty2.map(y => y[0] * y[1] * y[2])[0]


## 138688160
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