01: Trebuchet?!

library(mistlecode)

options(scipen = 999)

dt <- readLines("input.txt")

Part 1

This wasn’t too bad. Just forgot to unlist initially.

dt |>
   sapply(\(x) {
     x |>
      str_extract_all('[0-9]') |>
      unlist() -> y
    glue::glue('{head(y, 1)}{tail(y, 1)}')
  }) |>
  as.numeric() |>
  sum()

[1] 56397

Part 2

This took way too long and I hate incomplete examples. Absolutely no indication that oneight flips for both 1 and 8.

numbers <-
  c(
    'one' = 1,
    'two' = 2,
    'three' = 3,
    'four' = 4,
    'five' = 5,
    'six' = 6,
    'seven' = 7,
    'eight' = 8,
    'nine' = 9
  )
dt |>
  sapply(\(x) {
    n <- c(names(numbers), '[1-9]')
    i <-
      x |>
      stringi::stri_locate_all_regex(n, omit_no_match = TRUE) |>
      lapply(data.frame) |>
      purrr::list_rbind() |>
      dplyr::pull(start) |>
      order()
    x <-
      stringi::stri_match_all_regex(x, n) |>
      unlist() |>
      purrr::discard(is.na)
    y <- ifelse(x %in% names(numbers), numbers[x], x)[i]
    glue::glue('{head(y, 1)}{tail(y, 1)}')
  }) |>
  as.numeric() |>
  sum()

[1] 55701