Advent of Code 2024: Day 3

AoC_2024_Day3.R

library(tidyverse)
input <- readLines("input")

##### Part 1 #####

vals <- tibble(
  mul = str_match_all(paste(input, collapse = ""), 
                      "(mul\\(\\d{1,3},\\d{1,3}\\))")[[1]][,2]) %>% 
  mutate(val1 = as.numeric(str_match(mul, "\\((\\d{1,3})\\,")[,2]),
         val2 = as.numeric(str_match(mul, "\\,(\\d{1,3})\\)")[,2])) %>% 
  mutate(product = val1*val2)

sum(vals$product)


##### Part 2 #####

vals <- vals %>% 
  mutate(start = str_locate_all(paste(input, collapse = ""),
               "mul\\(\\d{1,3},\\d{1,3}\\)")[[1]][,1])

cond_true <- tibble(
  start = str_locate_all(paste(input, collapse = ""), 
                      "do\\(\\)")[[1]][,1] )

cond_false <- tibble(
  start = str_locate_all(paste(input, collapse = ""), 
                        "don\\'t\\(\\)")[[1]][,1] )

cond <- bind_rows(cond_true  %>% mutate(condition = TRUE), 
                  cond_false %>% mutate(condition = FALSE))

vals_cond <- full_join(vals, cond) %>% 
  arrange(start) %>% 
  mutate(n = 1:n()) %>% 
  mutate(condition = ifelse(n == 1, TRUE, condition)) %>% 
  fill(condition) %>% 
  filter(condition) %>% 
  filter(!is.na(product))

sum(vals_cond$product)