Day 1 & 2

Author: stevenhorsman

Diff for: .editorconfig

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+root = true;
+
+[*]
+indent_style = space
+indent_size = 2
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true

Diff for: .eslintrc.js

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+module.exports = {
+  "env": {
+    "es6": true,
+    "node": true,
+    "mocha": true
+  },
+  "extends": "eslint:recommended",
+  "parserOptions": {
+    "sourceType": "module"
+  },
+  "rules": {
+    "indent": ["error", 2, { "SwitchCase": 1 }],
+    "quotes": [2, "single"],
+    "semi": 2
+  }
+};

Diff for: .gitignore

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+node_modules/
+
+input.js

Diff for: .npmrc

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+package-lock=false

Diff for: .travis.yml

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+language: node_js
+node_js:
+- '8'
+script:
+- npm run lint
+- npm test

Diff for: .vscode/launch.json

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+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "node",
+            "request": "launch",
+            "name": "Launch Program",
+            "program": "${workspaceFolder}\\index.js"
+        }
+    ]
+}

Diff for: LICENSE

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+MIT License
+
+Copyright (c) 2018 Mario Tacke
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Diff for: README.md

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+# Advent of Code 2018 
+
+My repo for Advent of Code 2018 in nodejs/javascript. I'm using this as an excuse to work on my javascript, so this shouldn't be used as an example of the best way to do it.
+
+Tests inspired by: https://github.com/mariotacke/advent-of-code-2018
+
+Dev code starts as my own, but I will look at other solutions for inspiration of how to do it better after.
+
+## Running Tests
+
+Each day contains its own set of tests. To run them type `npm test`.
+
+## Visit
+- http://adventofcode.com/2018

Diff for: day-01-chronal-calibration/README.md

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+# Day 1: Chronal Calibration
+
+After feeling like you've been falling for a few minutes, you look at the device's tiny screen. "Error: Device must be calibrated before first use. Frequency drift detected. Cannot maintain destination lock." Below the message, the device shows a sequence of changes in frequency (your puzzle input). A value like `+6` means the current frequency increases by `6`; a value like `-3` means the current frequency decreases by `3`.
+
+For example, if the device displays frequency changes of `+1, -2, +3, +1`, then starting from a frequency of zero, the following changes would occur:
+
+- Current frequency ` 0`, change of `+1`; resulting frequency ` 1`.
+- Current frequency ` 1`, change of `-2`; resulting frequency `-1`.
+- Current frequency `-1`, change of `+3`; resulting frequency ` 2`.
+- Current frequency ` 2`, change of `+1`; resulting frequency ` 3`.
+
+In this example, the resulting frequency is `3`.
+
+Here are other example situations:
+
+- `+1, +1, +1` results in ` 3`
+- `+1, +1, -2` results in ` 0`
+- `-1, -2, -3` results in `-6`
+
+Starting with a frequency of zero, **what is the resulting frequency** after all of the changes in frequency have been applied?
+
+## Part Two
+
+You notice that the device repeats the same frequency change list over and over. To calibrate the device, you need to find the first frequency it reaches **twice**.
+
+For example, using the same list of changes above, the device would loop as follows:
+
+- Current frequency ` 0`, change of `+1`; resulting frequency ` 1`.
+- Current frequency ` 1`, change of `-2`; resulting frequency `-1`.
+- Current frequency `-1`, change of `+3`; resulting frequency ` 2`.
+- Current frequency ` 2`, change of `+1`; resulting frequency ` 3`.
+- (At this point, the device continues from the start of the list.)
+- Current frequency ` 3`, change of `+1`; resulting frequency ` 4`.
+- Current frequency ` 4`, change of `-2`; resulting frequency ` 2`, which has already been seen.
+
+In this example, the first frequency reached twice is `2`. Note that your device might need to repeat its list of frequency changes many times before a duplicate frequency is found, and that duplicates might be found while in the middle of processing the list.
+
+Here are other examples:
+
+- `+1, -1` first reaches `0` twice.
+- `+3, +3, +4, -2, -4` first reaches `10` twice.
+- `-6, +3, +8, +5, -6` first reaches `5` twice.
+- `+7, +7, -2, -7, -4` first reaches `14` twice.
+
+**What is the first frequency your device reaches twice?**
+
+## References
+- https://adventofcode.com/2018/day/1

Diff for: day-01-chronal-calibration/chronal-calibration.js

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+function calculateFrequency(input) {
+    let result = 0;
+    input.split(/\r?\n/).forEach(change => {
+        result += parseInt(change);
+    });
+    return result;
+
+    //Better:
+    // return input
+    // .split('\n')
+    // .map((x) => parseInt(x))
+    // .reduce((a, b) => a + b, 0);
+  }
+
+function calculateFrequencyFoundTwice(input) {
+    const frequencies = new Set([0]);
+    let result = 0;
+    let repetitionFound = false;
+
+    const changes = input
+    .split('\n')
+    .map((x) => parseInt(x));
+
+    while (!repetitionFound) {
+        for (let i=0; i<changes.length; i++) {
+            result += changes[i];
+           if (frequencies.has(result)) {
+                repetitionFound = true;
+               break;
+            }
+            frequencies.add(result);
+        }
+    }
+    return result;
+  }
+   
+module.exports.calculateFrequency = calculateFrequency;
+module.exports.calculateFrequencyFoundTwice = calculateFrequencyFoundTwice;