Day 10

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AUTO-ACQUIRED DATA FOLLOWS...

(asdf:load-system :split-sequence)
    (asdf:load-system :iterate)
    (defpackage #:aoc-10
      (:use #:cl #:split-sequence #:iterate))
    (in-package #:aoc-10)
    
    (defun getinput ()
        (mapcar (lambda (x)
                    (parse-integer x))
          (uiop:read-file-lines "bigboy.txt")))
    
    (defun part1 ()
        (let* ((input (sort (getinput) #'<))
               (proc 
                 (mapcar (lambda (x y)
                           (- y x))
                   (cons 0 (subseq input 0 (length input) ))
                   (nreverse 
                     (cons (+ (car (last input)) 3) 
                           (nreverse input) )))))
          (* (count 1 proc)
             (count 3 proc))))
    
    (defun part2-walk (l cache)
        (if (not (cadr l)) 
         1
         (reduce #'+ 
           (mapcar 
             (lambda (remain) 
              (if (and 
                    (car remain) 
                    (<= (- (car remain) (car l)) 3))
                (multiple-value-bind 
                  (result exists)
                  (gethash (car remain) cache)
                  (if exists result
                      (setf (gethash (car remain) cache)
                          (part2-walk remain cache))))
                0))
             `(,(cdr l) ,(cddr l) ,(cdddr l))))))
    
    (defun part2-slow ()
        (let* ((input (cons 0 
                        (append (sort (getinput) #'<)
                          (list 
                            (+ 3 
                               (apply #'max 
                                      (getinput)))))))
               (mycache (make-hash-table :test #'equal)))
          (part2-walk input mycache)))
    
    (defun validp (a b)
        (<= (- b a) 3))
    
    (defun getif (val later)
        (if (validp val (car later))
            (cadr later)
            0))
    
    (defun part2 ()
      (let* ((input (nreverse (cons 0 (sort (getinput) #'<))))
             (tri (list (pop input) 1))
             (two (list (pop input) 1))
             (one-f (pop input))
             (one (list one-f
                        (+ (getif one-f two)
                           (getif one-f tri)))))
        (iterate (while input)
          (let* ((newval (pop input))
                 (new (list newval
                            (reduce #'+
                              (mapcar 
                                (lambda (x)
                                  (getif newval x))
                                (list tri two one))))))
            (setf tri (copy-list two)) 
            (setf two (copy-list one)) 
            (setf one (copy-list new))))
        (log (cadr one) 10)))

day-10/day10.lisp

(defun load-nums (filename)
        (with-open-file (stream filename)
            (loop for line = (read-line stream nil)
                while line
                collect (parse-integer line))))
    
    (defun differences (nums)
        (if (cdr nums) ; length >= 2
            (cons
                (- (car nums) (cadr nums))
                (differences (cdr nums)))))
    
    (defun find-paths (remaining-nodes alist)
        ; alist stores number of paths from some nodes
        (let* ((current-node (car remaining-nodes))
               (options (list
                    (assoc (+ current-node 1) alist)
                    (assoc (+ current-node 2) alist)
                    (assoc (+ current-node 3) alist)))) ; some options may be nil
            (let* ((path-sum (reduce '+ (mapcar (lambda (x) (if (null x) 0 (cdr x))) options)))
                   (paths (if (= 0 path-sum)
                    1 ; this must be the first go-through
                    path-sum)))
                (if (= current-node 0)
                    paths
                    (find-paths (cdr remaining-nodes) (acons current-node paths alist))))))
    
    (let* ((input-nums (sort (load-nums "input10.txt") '>))
           (lowest-num 0) (highest-num (+ 3 (car input-nums)))
           (all-nums (append (list highest-num) input-nums (list lowest-num))))
        (let ((diffs (differences all-nums)))
            (format t "~a~%"
                (* (count-if (lambda (x) (= x 3)) diffs)
                   (count-if (lambda (x) (= x 1)) diffs))))
        (format t "~a~%"
            (find-paths all-nums '())))

javanon/day10.js

dataset = document.querySelector("body > pre");
    numbers = dataset.innerText.trim().split("\n").map(val => Number(val)).sort( (a, b) => a - b);
    
    function day10_partA (input) {
        var counts = input.map( (v, i, arr) => v - (arr[i - 1] || 1))
                     .reduce( (acc, item) => {
                         acc[item]++;
                         return acc;
                     }, {1: 1, 3: 1});
        return counts[1] * counts[3];
    }
    
    function day10_partB (input) {
        var sums = {0: 1};
        input.forEach(item => sums[item] = (sums[item - 3] || 0) + (sums[item - 2] || 0) + (sums[item - 1] || 0));
        return sums[input[input.length - 1]];
    }

steveklabnik/steveklabnik-day10.rs

fn solve(input: &str) -> (u32, u64) {
        let mut adapters: Vec<usize> = input.lines().map(|s| s.parse().unwrap()).collect();
        adapters.sort_unstable();
        let max = adapters.last().unwrap() + 3;
        adapters.push(max);
    
        let mut last = 0;
        let mut count = vec![0; max + 1];
        count[0] = 1;
    
        let a = adapters
            .iter()
            .inspect(|&&n| {
                count[n] = (1..=3)
                    .filter_map(|d| n.checked_sub(d).map(|n| count[n]))
                    .sum()
            })
            .map(|&n| n - std::mem::replace(&mut last, n))
            .fold((0, 0), |(a, b), d| {
                (a + u32::from(d == 1), b + u32::from(d == 3))
            });
    
        (a.0 * a.1, count[max])
    }

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