commit d2c86eae09a49a747e13e8f050b8fcbc163a44b2
parent d3860d3b6c58fb2fd8fa8ffc3b2760c6cd32195b
Author: Eamon Caddigan <ec@eamoncaddigan.net>
Date: Wed, 3 Dec 2025 09:30:59 -0800
Solve day 02, part 1
Diffstat:
| A | src/day03.R | | | 48 | ++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 48 insertions(+), 0 deletions(-)
diff --git a/src/day03.R b/src/day03.R
@@ -0,0 +1,48 @@
+#!/usr/bin/env Rscript
+
+source("src/utils.R")
+
+test_input <- c(
+ "987654321111111",
+ "811111111111119",
+ "234234234234278",
+ "818181911112111"
+)
+puzzle_input <- aoc_input(3)
+
+parse_input <- function(input_lines) {
+ input_lines |>
+ strsplit("", fixed = TRUE) |>
+ lapply(as.numeric)
+}
+
+choose_batteries <- function(battery_bank) {
+ first_battery_loc <- which.max(battery_bank[1:(length(battery_bank) - 1)])
+ second_battery_loc <- first_battery_loc +
+ which.max(battery_bank[(first_battery_loc + 1):length(battery_bank)])
+ c(first_battery_loc, second_battery_loc)
+}
+
+use_batteries <- function(battery_bank, battery_choice) {
+ battery_bank[battery_choice] |>
+ paste(collapse = "") |>
+ as.numeric()
+}
+
+part1 <- function(input_string) {
+ input_string |>
+ parse_input() |>
+ (\(x) mapply(use_batteries, x, lapply(x, choose_batteries)))() |>
+ sum()
+}
+
+test_part1 <- function() {
+ stopifnot(part1(test_input) == 357)
+}
+
+main <- function() {
+ test_part1()
+ cat("Part 1 solution: ", part1(puzzle_input), "\n")
+}
+
+main()
