Advent of Code 2021 day 1

day01.clj

;; https://adventofcode.com/2021/day/1

(ns day01
  (:require [clojure.string :as str]))

(def input (map #(Integer/parseInt %) (str/split-lines (slurp "day01.txt"))))

;; this is like levels of tired->wired etc...
;; there was a loop-based solution in https://www.youtube.com/watch?v=q_I3r0JGhR8 by onthecodeagain
;; which received some comments from Erik Grundy and Sebastian Anklamm offering a more functional solution: 

(defn part-1 [coll]
  (->> coll
       (partition 2 1)
       (map (fn [[x y]] (- x y)))
       (filter #(neg? %))
       (count)))

(defn part-2 [nums]
  (->> nums
       (partition 3 1)
       (map #(apply + %))
       (partition 2 1)
       (map #(apply < %))
       (filter identity)
       count))

(part-2 input)

;;@borkdude's "where's the rest of the code?" solution:
(map < input (rest input))
(map + input (next input) (nnext input))

tonsky's solution is essentially the same as borkdude's, just with more ceremony:

https://github.com/tonsky/advent-of-code/blob/main/src/advent_of_code/year2021/day1.clj

The big takeaway is that mapping on multiple collections is incredibly useful. Use it.

Solution using loop by Daniel from OnTheCodeAgain https://gist.github.com/danownsthisspace/671596eb4010f62c8dda7a7e61a853ee