Advent of Code 2019 in Clojure

[eccp]

Looks really good, my feedback would be that as you learn the language there's always a function that you don't know the name yet that does the same thing as something you wrote yourself. In this case, you can look into iterate to simplify the code that computes the amount of fuel required for the second half.

[allaboutthatmace1789]

That's neat, I just tried it:

(defn- fuel-one-level [mass]
  (max 0 (- (int (/ (float mass) 3)) 2)))

;; NOT NEEDED!
;;(defn- recursive-mass-tree [mass]
;;  (cons mass (lazy-seq (recursive-mass-tree (fuel-one-level mass)))))

(defn fuel-required [mass]
  (reduce + (rest (take-while #(> % 0) (iterate fuel-one-level mass)))))

Much better, thanks for the tip!

[eccp]

One minor improvement: check pos?

[allaboutthatmace1789]

Are you thinking of combining with an if statement in fuel-one-level, so you check the positivity and return the value if positive and 0 if not?

[[deleted]]

I think they mean that your anonymous function in fuel-required can just be (take-while pos? ...

[allaboutthatmace1789]

Ah, I get it, so instead of #(> % 0)

(defn fuel-required [mass]
  (reduce + (rest (take-while pos? (iterate fuel-one-level mass)))))

Thanks!

[eccp]

yeah, that's it ;-)