AoC 2021: Day 1

Day 1: Sonar Sweep

Click for Problem Statement

Back to 2021

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library(tidyverse)
library(here)

input <- tibble(first = as.numeric(read_lines(here("2021/inputs/01-input.txt"))))

Part 1

part_1 <- input %>% 
  mutate(prev = lag(first)) %>% 
  select(prev, first) %>% 
  mutate(change = first > prev) %>% 
  fill(change, .direction = "up")

part_1 %>% 
  summarise(sum(change))

## # A tibble: 1 × 1
##   `sum(change)`
##           <int>
## 1          1226

Part 2

part_2 <- input %>% 
  mutate(second = lag(first),
         third = lag(second)) %>% 
  mutate(total = first + second + third) %>% 
  mutate(change = total > lag(total))

part_2 %>% 
  summarise(sum(change, na.rm = TRUE))

## # A tibble: 1 × 1
##   `sum(change, na.rm = TRUE)`
##                         <int>
## 1                        1252