06: Tuning Trouble

library(tidyverse)
library(data.table)
library(mistlecode)

dt <- 
  'input.txt' |> 
  readLines() |> 
  strsplit('') |> 
  unlist()

This looks easy. Oh wait. I totally misread the problem…

do_part <- function(part) {
  part <- part - 1
  get_vec <- function(vec, place) {
    if (place == 0) { return(vec)}
    c(vec[-1:(-place)], rep(NA, place))
  }
  
  lapply(0:part, function(x) {
    get_vec(dt, x)
  }) |>
    data.frame() |>
    `colnames<-`(paste0("X", 1:part)) %>%
    apply(1, function(x) {
      paste0(x, collapse = "")
    }) |>
    sapply(function(x) {
      max(table(strsplit(x, "")))
    }) -> tmp
  (which(tmp == 1) + part)[1]
}

Part 1

Hardcoding everything will bite me in the butt later probably. Ultimately not too bad in hindsight.

New

do_part(4)

bdjq 
1578 

Original

data.frame("w" = dt,
           "x" = c(dt[-1], NA),
           "y" = c(dt[-1:-2], NA, NA),
           "z" = c(dt[-1:-3], NA, NA, NA)) |>
  mutate(marker = paste0(w, x, y, z, sep = "")) |>
  apply(1, function(x) {
    max(table(strsplit(x["marker"], "")))
  }) -> tmp
(which(tmp == 1) + 3)[1]

[1] 1578

Part 2

Well, well, well. Hardcoding is never a good move. Took a bit of time to get it figured out, but I got there in the end.

New

do_part(14)

mdcbnwqgshpvfj 
          2178 

Original

get_vec <- function(vec, place) {
  if (place == 0) { return(vec) }
  c(vec[-1:(-place)], rep(NA, place))
}

lapply(0:13, function(x) {
  get_vec(dt, x)
}) |>
  data.frame() |>
  `colnames<-`(paste0("X", 1:14)) %>%
  apply(1, function(x) {
    paste0(x, collapse = "")
  }) |>
  sapply(function(x) {
    max(table(strsplit(x, "")))
  }) -> tmp
(which(tmp == 1) + 13)[1]

mdcbnwqgshpvfj 
          2178