Advent of Code 2021 Day 7

advent_of_code_2021_day_7.R

library(tidyverse)

data <-
  read_lines("07/input.txt") %>%
  str_split(",") %>%
  .[[1]] %>%
  as.integer()

# part 1
# the optimal location to meet is exactly the median (think L1 space if you're mathy)
location <- median(data)
fuel <- sum(abs(data-location))


# part 2
# the optimal location allowing for non-integer spaces is exactly the mean, but since we have to
# round it to an integer you can try the floor and ceiling of that location
location <- mean(data)
fuel_func <- function(x,y) if(x==y) 0 else sum(1:(abs(x-y)))
location_floor <- sum(map_dbl(data,~fuel_func(.x,floor(location))))
location_ceiling <- sum(map_dbl(data,~fuel_func(.x,ceiling(location))))
min(location_floor, location_ceiling)