06: Probably a Fire Hazard

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 <- readLines("input.txt")

Warning in readLines("input.txt"): incomplete final line found on 'input.txt'

Part 1

dt <- data.frame("dir" = str_extract(dt, "off|on|toggle"),
                 "from" = str_extract(dt, "[0-9]{1,3},[0-9]{1,3}"),
                 "to" = str_extract(dt, "[0-9]{1,3},[0-9]{1,3}$"))
from <- str_split(dt$from, ",", simplify = TRUE)
dt$fromX <- as.numeric(from[,1]) + 1
dt$fromY <- as.numeric(from[,2]) + 1

to <- str_split(dt$to, ",", simplify = TRUE)
dt$toX <- as.numeric(to[,1]) + 1
dt$toY <- as.numeric(to[,2]) + 1

lights <- data.frame("x" = rep(1:1000, 1000), 
                     "y" = rep(1:1000, each = 1000),
                     "stat" = as.integer(0))

for(i in 1:nrow(dt)) {
  if(dt$dir[i] == "on") {
    lights$stat[dt$fromX[i] <= lights$x & 
                  dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & 
                  dt$toY[i] >= lights$y] <- 1
  }
  if(dt$dir[i] == "off") {
    lights$stat[dt$fromX[i] <= lights$x & 
                  dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & 
                  dt$toY[i] >= lights$y] <- 0
  }
  if(dt$dir[i] == "toggle") {
    lights$stat[dt$fromX[i] <= lights$x & dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & dt$toY[i] >= lights$y] <- 
      ifelse(lights$stat[dt$fromX[i] <= lights$x & dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & dt$toY[i] >= lights$y] == 1, 0, 1)
  }
}

nrow(lights[lights$stat == 1,])

[1] 400410

Part 2

# part 2
lights <- data.frame("x" = rep(1:1000, 1000), 
                     "y" = rep(1:1000, each = 1000),
                     "stat" = as.integer(0))

for(i in 1:nrow(dt)) {
  if(dt$dir[i] == "on") {
    lights$stat[dt$fromX[i] <= lights$x & 
                  dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & 
                  dt$toY[i] >= lights$y] <- lights$stat[dt$fromX[i] <= lights$x & 
                  dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & 
                  dt$toY[i] >= lights$y] + 1
  }
  if(dt$dir[i] == "off") {
    lights$stat[dt$fromX[i] <= lights$x & dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & dt$toY[i] >= lights$y] <- 
      ifelse(lights$stat[dt$fromX[i] <= lights$x & dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & dt$toY[i] >= lights$y] == 0, 
             lights$stat[dt$fromX[i] <= lights$x & dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & dt$toY[i] >= lights$y], 
             lights$stat[dt$fromX[i] <= lights$x & dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & dt$toY[i] >= lights$y] - 1)
  }
  if(dt$dir[i] == "toggle") {
    lights$stat[dt$fromX[i] <= lights$x & 
                  dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & 
                  dt$toY[i] >= lights$y] <- lights$stat[dt$fromX[i] <= lights$x & 
                  dt$toX[i] >= lights$x & 
                  dt$fromY[i] <= lights$y & 
                  dt$toY[i] >= lights$y] + 2
  }
}

sum(lights$stat)

[1] 15343601