02: I Was Told There Would Be No Math

library(tidyverse)

── Attaching packages ─────────────────────────────────────── tidyverse 1.3.2 ──
✔ ggplot2 3.4.0      ✔ purrr   0.3.5 
✔ tibble  3.1.8      ✔ dplyr   1.0.10
✔ tidyr   1.2.1      ✔ stringr 1.4.1 
✔ readr   2.1.3      ✔ forcats 0.5.2 
── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
✖ dplyr::filter() masks stats::filter()
✖ dplyr::lag()    masks stats::lag()

library(stringr)

dt <- data.table::fread("input.txt", sep = "x")

Part 1

# part 1
tmp <- dt %>%
  .[, c("l", "w", "h") := .(V1 * V2, V2 * V3, V1 * V3)] %>%
  .[, min := ifelse(l <= w & l <= h, l, 
                    ifelse(w <= l & w <= h, w, h))] %>%
  .[, sq := 2*l + 2*w + 2*h + min]
sum(tmp$sq, na.rm = TRUE)

[1] 1598415

Part 2

tmp <- dt %>%
  .[, c("l", "w", "h") := .(V1 * V2, V2 * V3, V1 * V3)]
tmp <- tmp[, c("l", "w", "h") := .(V1, V2, V3)] %>%
  .[, max := apply(dt[, .(l, w, h)], 1, max)] %>%
  rowwise() %>%
  mutate(test = list(c(l, w, h)))
tmp$min1 <- t(data.frame(sapply(tmp$test, sort)))[,1]
tmp$min2 <- t(data.frame(sapply(tmp$test, sort)))[,2]

tmp <- data.table::data.table(tmp)[,rib := ((2*min1 + 2*min2) + (V1 * V2 * V3))]
sum(tmp$rib, na.rm = TRUE)

[1] 3812909