Solving Advent of Code 2019-04 with R and JavaScript.
[Disclaimer] Obviously, this post contains a big spoiler about Adventof Code, as it gives solutions for solving day 4.
[Disclaimer bis] I’m no JavaScript expert so this might not be theperfect 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 Rcode. It runs thanks to the {bubble} package:https://github.com/ColinFay/bubble
Instructions
Find the instructions at: https://adventofcode.com/2019/day/4
R solution
Part one
test <- 156218:652527 library(magrittr) cond <- function(vec){ splt <- strsplit( as.character(vec), "")[[1]] %>% as.numeric() adj_eq <- (splt == dplyr::lag(splt))[-1] incre <- (splt >= dplyr::lag(splt))[-1] any(adj_eq) & all(incre) } vapply(test, cond, logical(1)) %>% sum() ## [1] 1694 Part two
cond2 <- function(vec){ splt <- strsplit( as.character(vec), "")[[1]] %>% as.numeric() adj_eq <- (splt == dplyr::lag(splt))[-1] if (any(adj_eq)){ adj_eq <- any(table(splt) == 2) } incre <- (splt >= dplyr::lag(splt))[-1] any(adj_eq) & all(incre) } vapply(test, cond2, logical(1)) %>% sum() ## [1] 1148 JS solution
Part one & Two
// Generating the array (fromhttps://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from)
const range = (start, stop, step = 1) => Array.from({ length: (stop - start) / step + 1}, (_, i) => start + (i * step)); var test = range(156218, 652527) function lag(vec){ var res = []; res.push(null); for (var i = 0; i < vec.length - 1; i ++){ res.push(vec[i]) } return res } function cond(vec){ var vec = vec.toString().split("").map(x => parseInt(x)); var laged = lag(vec); var adj_eq = vec.map( (x, i) => x == laged[i] ) adj_eq.shift() var adj_eq = adj_eq.some(z => z); var incre = vec.map( (x, i) => x >= laged[i] ) incre.shift() var incre = incre.every(z => z); var all = [incre, adj_eq].every(z => z); return all } test.map(cond).filter(v => v).length ## 1694 function table(vec){ var tbl = {} vec.map(function(x){ if (tbl[x]){ tbl[x] = tbl[x] + 1; } else { tbl[x] = 1; } }) return tbl } function cond2(vec){ var vec = vec.toString().split("").map(x => parseInt(x)); var laged = lag(vec); var adj_eq = vec.map( (x, i) => x == laged[i] ) adj_eq.shift() var adj_eq = adj_eq.some(z => z); if (adj_eq){ var tb = table(vec); var res = []; for (i in tb){ res.push(tb[i] == 2); } var adj_eq = res.some(x => x); } var incre = vec.map( (x, i) => x >= laged[i] ); incre.shift(); var incre = incre.every(z => z); var all = [incre, adj_eq].every(z => z); return all; } test.map(cond2).filter(v => v).length; ## 1148 
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