Advent of Code 2019-01 with R & JavaScript

November 30, 2019
By

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Solving Advent of Code 2019-01 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

Find the instructions at: https://adventofcode.com/2019/day/1

R solution

Part one

# Read
ipt <- read.delim( "input1.txt",  header = FALSE )
# Get the sum of each element, divided by 3, rounded down, and substracted 2
sum( floor( ipt$V1 / 3) - 2 )
## [1] 3361299

Part two

Using a recursive function:
https://en.wikipedia.org/wiki/Recursion_(computer_science)

floorish <- function(x, start = 0){
  loc <- floor( x / 3) - 2
  if (loc > 0){
    start <- start + loc
    floorish(loc, start)
  } else {
    return(start)
  } 
}
sum( purrr::map_dbl(ipt$V1, floorish) )
## [1] 5039071

JS solution

Part one & Two

var fs = require('fs');

// Reading the file
var res = fs.readFileSync("input1.txt", 'utf8').split("\n").filter(x => x.length != 0);

// Turning to integer
res = res.map(x => parseInt(x));

// Doing the floor of division less 2
var val = res.map(x => Math.floor(x / 3) - 2);

// Suming
var add = (x, y) => x + y;

// Solution
console.log( val.reduce(add) );

// Creating the recursive function
function floorish(val, start = 0){
  loc = Math.floor(val / 3) - 2;
  if (loc > 0){
    start += loc;
    return floorish(loc, start);
  } else {
    return start;
  } 
}

// Doing the computation
console.log( res.map( x => floorish(x) ).reduce( add ) );
## 3361299
## 5039071

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