feat: Day 23: Experimental Emergency Teleportation (part 1)

Author: mariotacke

Diff for: .github/badges/completion.json

@@ -1,6 +1,6 @@
 {
   "schemaVersion": 1,
   "label": "completion",
-  "message": "35/50",
+  "message": "36/50",
   "color": "yellow"
 }

Diff for: README.md

@@ -31,6 +31,7 @@ Collect stars by solving puzzles. Two puzzles will be made available on each day
 - [Day 15: Beverage Bandits](day-15-beverage-bandits/)
 - [Day 16: Chronal Classification](day-16-chronal-classification/)
 - [Day 18: Settlers of The North Pole](day-18-settlers-of-the-north-pole/)
+- [Day 23: Experimental Emergency Teleportation](day-23-experimental-emergency-teleportation/)
 - [Day 25: Four-Dimensional Adventure](day-25-four-dimensional-adventure/)
 
 ## Running Tests

Diff for: day-23-experimental-emergency-teleportation/README.md

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+# Day 23: Experimental Emergency Teleportation
+
+Using your torch to search the darkness of the rocky cavern, you finally locate the man's friend: a small **reindeer**.
+
+You're not sure how it got so far in this cave. It looks sick - too sick to walk - and too heavy for you to carry all the way back. Sleighs won't be invented for another 1500 years, of course.
+
+The only option is **experimental emergency teleportation**.
+
+You hit the "experimental emergency teleportation" button on the device and push **I accept the risk** on no fewer than 18 different warning messages. Immediately, the device deploys hundreds of tiny **nanobots** which fly around the cavern, apparently assembling themselves into a very specific **formation**. The device lists the `X,Y,Z` position (`pos`) for each nanobot as well as its **signal radius** (`r`) on its tiny screen (your puzzle input).
+
+Each nanobot can transmit signals to any integer coordinate which is a distance away from it **less than or equal** to its signal radius (as measured by [Manhattan distance](https://en.wikipedia.org/wiki/Taxicab_geometry)). Coordinates a distance away of less than or equal to a nanobot's signal radius are said to be **in range** of that nanobot.
+
+Before you start the teleportation process, you should determine which nanobot is the **strongest** (that is, which has the largest signal radius) and then, for that nanobot, the **total number of nanobots that are in range** of it, **including itself**.
+
+For example, given the following nanobots:
+
+```
+pos=<0,0,0>, r=4
+pos=<1,0,0>, r=1
+pos=<4,0,0>, r=3
+pos=<0,2,0>, r=1
+pos=<0,5,0>, r=3
+pos=<0,0,3>, r=1
+pos=<1,1,1>, r=1
+pos=<1,1,2>, r=1
+pos=<1,3,1>, r=1
+```
+
+The strongest nanobot is the first one (position `0,0,0`) because its signal radius, `4` is the largest. Using that nanobot's location and signal radius, the following nanobots are in or out of range:
+- The nanobot at `0,0,0` is distance `0` away, and so it is **in range**.
+- The nanobot at `1,0,0` is distance `1` away, and so it is **in range**.
+- The nanobot at `4,0,0` is distance `4` away, and so it is **in range**.
+- The nanobot at `0,2,0` is distance `2` away, and so it is **in range**.
+- The nanobot at `0,5,0` is distance `5` away, and so it is **not** in range.
+- The nanobot at `0,0,3` is distance `3` away, and so it is **in range**.
+- The nanobot at `1,1,1` is distance `3` away, and so it is **in range**.
+- The nanobot at `1,1,2` is distance `4` away, and so it is **in range**.
+- The nanobot at `1,3,1` is distance `5` away, and so it is not **in range**.
+
+In this example, in total, **`7`** nanobots are in range of the nanobot with the largest signal radius.
+
+Find the nanobot with the largest signal radius. **How many nanobots are in range** of its signals?
+
+## References
+- https://adventofcode.com/2018/day/23

Diff for: day-23-experimental-emergency-teleportation/teleport.js

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+function distance(v0, v1) {
+  return v0.reduce((sum, _, i) => sum + Math.abs(v0[i] - v1[i]), 0);
+}
+
+module.exports = (input) => {
+  const nanobots = input.split('\n').map((line) => {
+    return {
+      vector: /<(.*)>/.exec(line)[1].split(',').map((value) => parseInt(value)),
+      radius: parseInt(/r=(\d+)/.exec(line)[1]),
+    };
+  });
+
+  const { vector, radius } = nanobots.sort((a, b) => b.radius - a.radius)[0];
+
+  return nanobots.reduce((numberInRange, { vector: otherVector }) => {
+    return numberInRange + (distance(vector, otherVector) <= radius ? 1 : 0);
+  }, 0);
+};

Diff for: day-23-experimental-emergency-teleportation/test.js

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+const assert = require('assert');
+
+const teleport = require('./teleport');
+
+describe('Day 23: Experimental Emergency Teleportation', () => {
+  it('should determine number of nanobots in range of strongest', () => {
+    const nanobots =
+      `pos=<0,0,0>, r=4
+       pos=<1,0,0>, r=1
+       pos=<4,0,0>, r=3
+       pos=<0,2,0>, r=1
+       pos=<0,5,0>, r=3
+       pos=<0,0,3>, r=1
+       pos=<1,1,1>, r=1
+       pos=<1,1,2>, r=1
+       pos=<1,3,1>, r=1`;
+
+    assert.strictEqual(teleport(nanobots), 7);
+  });
+});