Day 1: Historian Hysteria

library(tidyverse)

dat <- read.table("aoc01.txt")

Part 1

sortdat <- data.frame(V1 = sort(dat$V1), V2 = sort(dat$V2)) |>
  mutate(dist = abs(V1 - V2))
sum(sortdat$dist)

[1] 1590491

Part 2

tally_right <- dat |>
  group_by(V2) |>
  tally() |>
  rename(V1 = V2)

left <- dat |>
  select(V1) |>
  left_join(tally_right) |>
  replace_na(list(n = 0)) |>
  mutate(sim = V1 * n)

Joining with `by = join_by(V1)`

sum(left$sim)

[1] 22588371