AOC2022 Day1

Sample input for the Day 1 (input.txt)

1000
2000
3000

4000

5000
6000

7000
8000
9000

10000

Part 1

• We need to add all the numbers until there is empty line and find out which is the max value.

(defn part1 [file]
  
  (let [input (clojure.string/split-lines (slurp file))
        max-number (atom 0)]

  (loop [counter 0 
         elements input]
    (let [element (first elements)]
      (if (nil? element)
        @max-number
        (if (clojure.string/blank? element)
          (do (swap! max-number max counter)
              (recur 0 (rest elements)))
          (recur (+ counter (Integer/parseInt element)) (rest elements))))))))

(part1 "input.txt")

• I loop through the element and add it to counter.
• when there is empty line, choose the max(max-number, counter) and reset the counter.
• None (first elements) is nil we return the max-number

Part 2

• We need to add all the numbers until there is empty line and find out which is the first 3 max value and add them together.

(defn part2 [file]
  
  (let [input (clojure.string/split-lines (slurp file))
        max-number (atom [])]

  (loop [counter 0 
         elements input]
    (let [element (first elements)]
      (if (nil? element)
        @max-number
        (if (clojure.string/blank? element)
          (do (swap! max-number conj counter)
              (recur 0 (rest elements)))
          (recur (+ counter (Integer/parseInt element)) (rest elements))))))))

(apply + (take 3 (sort > (part2 "input.txt"))))

• I loop through the element and add it to counter.
• when there is empty line, append to the max-number list and reset the counter.
• None (first elements) is nil we return the max-number list
• sort the list in descending order, take 3 element and apply sum on those

Learned from others

• (str/split input #"\n\n") we can use \n\n to take the content easily.
• (take-last 3 (sort <Collection>)) Another way to take 3 max numbers from collection.
• (parse-long "56") convert string to number in clojure

Reference

• https://github.com/Teekeks/AoC2022/blob/master/src/de/teawork/aoc2022/day/01.clj
  • I learned about new library Fluokitten in this repo (category theory in clojure).
• https://github.com/vollcheck/aoc/blob/master/src/y22/day01.clj
• https://github.com/Akallabet/aoc-clojure/blob/main/day-1/day-1.clj