Advent of Code 2020 Day 7

— Day 7: Handy Haversacks —

Aviation rules are being enforced about bags and bags inside bags etcetera.

How many bag colors can eventually contain at least one shiny gold bag? (The list of rules is quite long; make sure you get all of it.)

library(tidyverse)

── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
✔ dplyr     1.1.4     ✔ readr     2.1.6
✔ forcats   1.0.1     ✔ stringr   1.6.0
✔ ggplot2   4.0.1     ✔ tibble    3.3.0
✔ lubridate 1.9.4     ✔ tidyr     1.3.1
✔ purrr     1.2.0     
── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::filter() masks stats::filter()
✖ dplyr::lag()    masks stats::lag()
ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors

my_file <- here::here("2020", "data-2020-07.txt")

# read file
lugg <- read.delim(my_file, header = FALSE)

bag <- "shiny gold"

Make some new columns in the df

# split
lugg2 <- separate(lugg, V1, into = c("first", "other"), sep = " bags contain ") %>% 
  mutate(others = as.vector(str_split(other, ", ")))

lugg2$contains <- str_detect(lugg2$first, bag)
lugg2$level <- if_else(lugg2$contains, 1, 0)
srch_lvl <- 1

Create a function then do loops

recurs_search <- function(df) {
  # things to search for
  srch_list <- df %>% 
    filter(contains == TRUE & level == srch_lvl) %>% 
    select(first) %>% 
    as.vector() 
  # increase level for efficiency (don't look twice)
  srch_lvl <<- srch_lvl + 1
  # print(srch_lvl)
  # print(length(srch_list$first))
  if (length(srch_list$first) == 0) {
    return(df)
  }
  # search for those things
  for (x in seq_along(srch_list$first)) {
    srch = srch_list$first[x]
    for (y in seq_along(df$other)) {
      if (str_detect(df$other[[y]], srch)) {
        df$contains[[y]] = TRUE
        df$level[[y]] = srch_lvl
      }
    }
  }
  # print(sum(df$contains))
  df = recurs_search(df)
}

lugg3 <- recurs_search(lugg2)

sum(lugg3$contains == TRUE) - 1 

[1] 332

— Part Two —

How many individual bags are required inside your single shiny gold bag?

# function to add rows to our collection dataframe
add_bags <- function(df, item, multi) {
  # exit early
  if (item == "no other bags.") return(df)
  # get the number from the string, but also the other number of bags containing this one
  bb = parse_number(item) * multi
  # split the string (trusting the strings are all the same)
  cc = str_split(item, " ")
  # combine 2nd and 3rd parts, again, trust in the system
  clr = paste(cc[[1]][2], cc[[1]][3])
  # the next row for our counter df
  rw = list(bags = bb, colour = clr)
  # otherwise if adding a number, add it to search for later
  df = rbind(df, rw)
  # return, of course
  return(df)
}

Start some things

# initiate some variables
bag_current <- "1 shiny gold bag"
keep_going <- TRUE
bag_level <- 1

# blank dataframe
count_bags_df <- tribble(~bags, ~colour)
# this is the main part of the pattern
# loop through bags counter
count_bags_df <- add_bags(count_bags_df, bag_current, 1)

# split
lugg_part2 <- separate(lugg, V1, into = c("first", "other"), sep = " bags contain ") %>% 
  mutate(others = as.vector(str_split(other, ", ")))

Now, loop

# loop all of the loops
while (keep_going) {
  
  # how many bags we are getting in the current one
  multi = count_bags_df$bags[[bag_level]]
  # current colour of the bag
  this_bag = count_bags_df$colour[[bag_level]]
  
  # look for bags
  srch_list <- lugg_part2 %>% 
    filter(first == this_bag) %>% 
    select(others) %>% 
    unlist(use.names = FALSE)
  
  # add the found bags into our search 
  for (x in seq_along(srch_list)) {
    count_bags_df = add_bags(count_bags_df, srch_list[[x]], multi)
  }
  
  # iterate
  bag_level = bag_level + 1
  
  # stop if we have no more bags to search for
  if (bag_level > nrow(count_bags_df)) {
    break
  }

}

# minus one because we don't count shiny gold
sum(count_bags_df$bags) - 1

[1] 10875