elixir(2023): Day 3 readme

Author: r0xsh

2023/elixir/03/README.md

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+# Day 3: Gear Ratios
+
+[https://adventofcode.com/2023/day/3](https://adventofcode.com/2023/day/3)
+
+## Description
+
+### Part One
+
+You and the Elf eventually reach a [gondola lift](https://en.wikipedia.org/wiki/Gondola_lift) station; he says the gondola lift will take you up to the _water source_, but this is as far as he can bring you. You go inside.
+
+It doesn't take long to find the gondolas, but there seems to be a problem: they're not moving.
+
+"Aaah!"
+
+You turn around to see a slightly-greasy Elf with a wrench and a look of surprise. "Sorry, I wasn't expecting anyone! The gondola lift isn't working right now; it'll still be a while before I can fix it." You offer to help.
+
+The engineer explains that an engine part seems to be missing from the engine, but nobody can figure out which one. If you can _add up all the part numbers_ in the engine schematic, it should be easy to work out which part is missing.
+
+The engine schematic (your puzzle input) consists of a visual representation of the engine. There are lots of numbers and symbols you don't really understand, but apparently _any number adjacent to a symbol_, even diagonally, is a "part number" and should be included in your sum. (Periods (`.`) do not count as a symbol.)
+
+Here is an example engine schematic:
+
+    467..114..
+    ...*......
+    ..35..633.
+    ......#...
+    617*......
+    .....+.58.
+    ..592.....
+    ......755.
+    ...$.*....
+    .664.598..
+    
+
+In this schematic, two numbers are _not_ part numbers because they are not adjacent to a symbol: `114` (top right) and `58` (middle right). Every other number is adjacent to a symbol and so _is_ a part number; their sum is _`4361`_.
+
+Of course, the actual engine schematic is much larger. _What is the sum of all of the part numbers in the engine schematic?_

README.md

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 ----
 
 - Elixir
+
+2023
+----
+
+- Elixir