Day 1: Trebuchet?!

Reference

library(tidyverse)

input <- read_lines(file = "inputs/2023/01.txt")

Part One

Solution

calibrations_digits <- tibble(original = input) |> 
    
    mutate(first       = str_extract(original, pattern = "\\d"),
           last        = str_extract(original, pattern = "\\d(?=\\D*$)"),
           calibration = as.integer(paste0(first, last)))

calibrations_digits |> 
    summarise(sum = sum(calibration)) |>
    pull(sum) |> 
    cat()
## 54338

Full Table

Part Two

Solution

convert_number <- function(x) {
    if (x %in% as.character(0:9))
        return(x)
    
    else {
        numbers <- c("one", "two", "three", "four", "five", "six",
                     "seven", "eight", "nine")
        
        return(as.character(match(x, numbers)))
    }
}

calibrations_all <- tibble(original = input) |> 
    mutate(first = str_extract(original, pattern = "\\d|one|two|three|four|five|six|seven|eight|nine"),
           # this has problems with overlaps (for example "2911threeninesdvxvheightwobm" matches "eight" not "two")
           #last  = str_extract(original,
           #                    pattern = "(\\d|one|two|three|four|five|six|seven|eight|nine)(?!.*(\\d|one|two|three|four|five|six|seven|eight|nine).*$)")
           original_rev = stringi::stri_reverse(original),
           last = str_extract(original_rev, pattern = "\\d|eno|owt|eerht|ruof|evif|xis|neves|thgie|enin"),
           last = stringi::stri_reverse(last)) |> 
    
    mutate(first = map_chr(first, convert_number),
           last  = map_chr(last, convert_number)) |> 
    
    mutate(calibration = as.integer(paste0(first, last)))

calibrations_all |> 
    summarise(sum = sum(calibration)) |> 
    pull(sum) |> 
    cat()
## 53389

Full Table