This topic is about Day 6 of the Advent of Code 2021 . We have a private leaderboard (shared with users of Erlang Forums ): https://adventofcode.com/2021/leaderboard/private/view/370884 The entry code is: 370884-a6a71927

I enjoyed this one! :smiley: defmodule Aoc.Y2021.Day06 do @moduledoc """ Solved https://adventofcode.com/2021/day/6 """ import Aoc.Helper.IO def run_part1(), do: get_input() |> solve_part1() def run_part2(), do: get_input() |> solve_part2() def solve_part1(data), do: solve(data, 80)…

I wish I analyzed input properties more before jumping to solving things. The same happened with Bingo, the solution looked different in my head before and after I realized it’s a 5x5 grid all the time.

Looking forward to what you come up with. I was thinking the same thing but got lazy (scared) and backed away.

I’m going to have to go to bed without solving it. My initial idea was Bn= B0 x 2^Kt where B0 is the original count for each timer value. K is 1/7 and t (for part 2) is 256 - the original timer value. Just calculate that for each original timer value and then add them together. Not sure how to make …

I solved Part I with a DynamicSupervisor and a process per a fish approach :slight_smile: I expected fish behavioral features are to be changed in Part II and boom.

It’s nice when it works on part 2 without modifications. Not the most clever solution but it’s fast enough! defmodule AdventOfCode.Day06 do def part1(input) do input |> parse_input() |> Enum.frequencies() |> pass_days(80) |> Map.values() |> Enum.sum() end def part2(in…

My solution: I used 2 maps to track two groups of fish. fish cycles 7 days, spawn cycles 9 days. I couldn’t figure a way to track of all fish at the same rate, so I split into two groups, each with a different “gestation” rate. Runs ~250ms on Apple M1. defmodule Advent.Y2021.D06 do @spec part_…

Looking at others, I see that updating the map key isn’t expensive, and performance is similar - probably the cleaner/nicer way to go!

My solution with Livebook: y2021/day-06.livemd

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Advent of Code 2021 - Day 6

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groovyda December 6, 2021, 9:53am 13

Really nice!