Read in our puzzle input:

day <- 4

input <- here::here(
  "2022", "input",
  paste0("day_", stringr::str_pad(day, 2, "left", "0"))
  ) |>
  readLines()

Part 1

inputs <- strsplit(input, ",") |>
  lapply(strsplit, split = "-")

compare_pairs <- function(l) {
  a <- as.numeric(l[[1]])
  b <- as.numeric(l[[2]])
  (a[1] >= b[1] & a[2] <= b[2]) | (b[1] >= a[1] & b[2] <= a[2]) 
}

inputs |>
  vapply(compare_pairs, TRUE) |>
  sum()

## [1] 494

Part 2

compare_pairs2 <- function(l) {
  a <- as.numeric(l[[1]])
  b <- as.numeric(l[[2]])
  length(intersect(seq(a[1], a[2]), seq(b[1], b[2]))) > 0
}

inputs |>
  vapply(compare_pairs2, TRUE) |>
  sum()

## [1] 833