2025 advent of code day 5

day_5.R

# day 5 2025
# first star
options(scipen = 999)
input <- lapply(strsplit(readLines("input.txt"), "-"), as.numeric)
fresh_ranges <- Filter(function(x) {length(x) == 2}, input)
ids <- Filter(function(x) {length(x) == 1}, input)

length(unique(unlist(mapply(function(id, range){which(id >= range[1] & id <= range[2])}, list(ids), fresh_ranges))))

# second star
# sort ranges, if next lower and upper bounds > range, replace original
# if not then compare just upper bound
fresh_ranges <- lapply(fresh_ranges, sort, decreasing = FALSE)

compare <- function(x, i){
  upper <- 0
  fresh_ids <- 0
  if (x[[i]][2] > upper) {
    if (x[[i]][1] > upper) {
      count <- diff(x[[i]]) + 1
    } else {
      count <- diff(c(upper, x[[i]][2]))
    }
    fresh_ids <- fresh_ids + count
    upper <- x[[i]][2]
  }
  return(ids)
}

sapply(seq_along(fresh_ranges), compare, x = fresh_ranges)[1]