Not Quite Lisp

#adventofcode #algorithms #programming #javascript

Advent of Code 2015 Day 1

Part 1

Ups and downs

Where will Santa end up?
What better way to find out than with reduce()!

My algorithm in JavaScript:

input.split("").reduce(
  (floor, direction) => floor += direction == "(" ? 1 : -1
, 0)

Part 1, a year ago

My algorithm in JavaScript:

function dayOnePart1(str) {
  return str.split("").reduce((acc, curr, i) => { 
    return curr == "(" ? acc + 1 : acc - 1; 
  }, 0)
}

Very similar to how I just did it
Although the ternary feels awkward now that I'm familiar with putting assignment in the first clause

Part 2

Finding the first negative

My algorithm in JavaScript:

let floor = 0, i = 0
while (floor !== -1) floor += input[i++] == "(" ? 1 : -1
return i

Part 2, a year ago

My algorithm in JavaScript:

function dayOnePart2(str) {
  let arr = str.split("")
  let firstBasement
  let acc = 0
  for (let i = 0; i < arr.length; i++) {
    if (acc == -1) {
      firstBasement = i
      break;
    }
    arr[i] == "(" ? acc += 1 : acc -= 1;
  }
  return firstBasement  
}

A for loop with a break in it? Yikes!
This feels so much more complicated!

I did it!!

I solved both parts!
In three lines of code, each!
Using syntax and techniques that I've grown much more familiar with throughout this experience!

Year in review

46 stars earned: tied with my personal best!
2 simulators built: tied with my lowest amount in a year!

Star count (2021-2015)

278/350: 79.4 - C+ - Passing grade, still!

Last words, until December, 2022

I set out with one main goal:

Attempt at least Part 1 of all 175 Days

I had other goals:

Learn new computer science concepts
Practice writing JavaScript
Practice Front-End Development by simulating highly-visual puzzles
Teach beginners the joys of programming
Document everything, especially frustrations, struggles, debugging, failed attempts, confusion and times that I cheated by resorting to any given Day's reddit Solution Megathread
Surprise myself by solving tremendously difficult puzzles - at least for my professionally-untrained skill level
Create a timeless series that, when discovered, can act as a silent partner along some other budding puzzle-solver's journey

Did I meet every goal? You bet!

Does this end here? Of course not!

This series will continue as long as Eric Wastl continues publishing more puzzles each December.

I encourage you to do like I did, and support Eric: