aoc_2024/day_2.R at main · bcrossman/aoc_2024 · GitHub

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library(tidyverse)
file <- readLines("./inputs/input2.txt")

## Part 1

tibble(value = file) %>%
  rowid_to_column() %>%
  separate_rows(value, sep = " ", convert = T) %>%
  group_by(rowid) %>%
  mutate(increasing_check = value>lag(value,1),
         decreasing_check = value<lag(value,1),
         dif_check = abs(value-lag(value,1))>=1 & abs(value-lag(value,1))<=3) %>%
  group_by(rowid) %>%
  summarise(increasing_check = all(increasing_check, na.rm = T),
            decreasing_check = all(decreasing_check, na.rm = T),
            dif_check = all(dif_check, na.rm = T)) %>%
  mutate(safe = (increasing_check|decreasing_check) & dif_check) %>%
  filter(safe) %>%
  nrow()


## Part 2
safe <-
tibble(value = file) %>%
  rowid_to_column() %>%
  separate_rows(value, sep = " ", convert = T) %>%
  group_by(rowid) %>%
  mutate(increasing_check = value>lag(value,1),
         decreasing_check = value<lag(value,1),
         dif_check = abs(value-lag(value,1))>=1 & abs(value-lag(value,1))<=3) %>%
  group_by(rowid) %>%
  summarise(increasing_check = all(increasing_check, na.rm = T),
            decreasing_check = all(decreasing_check, na.rm = T),
            dif_check = all(dif_check, na.rm = T)) %>%
  mutate(safe = (increasing_check|decreasing_check) & dif_check) %>%
  filter(safe) %>%
  pull(rowid)

max_try <-
tibble(value = file) %>%
  rowid_to_column() %>%
  filter(!(rowid %in% safe)) %>%
  separate_rows(value, sep = " ", convert = T) %>%
  group_by(rowid) %>%
  mutate(id = row_number()) %>%
  pull(id) %>% max()

for(i in 1:max_try){

  new_safe <-
    tibble(value = file) %>%
    rowid_to_column() %>%
    filter(!(rowid %in% safe)) %>%
    separate_rows(value, sep = " ", convert = T) %>%
    group_by(rowid) %>%
    slice(-i) %>%
    mutate(increasing_check = value>lag(value,1),
           decreasing_check = value<lag(value,1),
           dif_check = abs(value-lag(value,1))>=1 & abs(value-lag(value,1))<=3) %>%
    group_by(rowid) %>%
    summarise(increasing_check = all(increasing_check, na.rm = T),
              decreasing_check = all(decreasing_check, na.rm = T),
              dif_check = all(dif_check, na.rm = T)) %>%
    mutate(safe = (increasing_check|decreasing_check) & dif_check) %>%
    filter(safe) %>%
    pull(rowid)

  safe <- c(safe, new_safe)

}

length(safe)