developher-net · developher-net · Dec 22, 2018 · Dec 20, 2018 · Dec 20, 2018 · Dec 20, 2018
diff --git a/2018/day-10/helpers.js b/2018/day-10/helpers.js
@@ -44,6 +44,7 @@ const parseLine = (input) => {
 }
 
 module.exports = {
+  listToProps: _listToProps,
   loadInput,
   parseLine
 }
diff --git a/2018/day-12/helpers.js b/2018/day-12/helpers.js
@@ -0,0 +1,30 @@
+const { listToProps } = require('../day-10/helpers')
+const fs = require('fs')
+const path = require('path')
+const filePath = path.join(__dirname, 'input.txt')
+const { linesToArray } = require('../inputParser')
+
+const loadInput = (callback) => {
+  fs.readFile(filePath, { encoding: 'utf8' }, (err, data) => {
+    if (err) throw err
+
+    const list = linesToArray(data).map(parseLine)
+    if (typeof callback === 'function') {
+      callback(list)
+    }
+  })
+}
+
+/**
+ * Parses a line from the input into structured data
+ * @param {String} input Line from input stream
+ * @returns Structured object with patterns and states
+ */
+const parseLine = (input) => {
+  return input.split(' => ').reduce((acc, curr, idx) => listToProps(acc, curr, idx, ['id', 'generate']), {})
+}
+
+module.exports = {
+  loadInput,
+  parseLine
+}
diff --git a/2018/day-12/helpers.test.js b/2018/day-12/helpers.test.js
@@ -0,0 +1,21 @@
+/* eslint-env mocha */
+const expect = require('chai').expect
+const {
+  parseLine
+} = require('./helpers')
+
+describe('--- Day 12: Subterranean Sustainability ---', () => {
+  describe('Helpers:', () => {
+    describe('parseLine(input)', () => {
+      it('converts a line of the input into structured object', () => {
+        const test = `..#.. => #`
+        const expected = {
+          id: '..#..',
+          generate: '#'
+        }
+        const actual = parseLine(test)
+        expect(actual).to.deep.equal(expected)
+      })
+    })
+  })
+})
diff --git a/2018/day-12/input.txt b/2018/day-12/input.txt
@@ -0,0 +1,32 @@
+.#### => .
+...#. => .
+.##.. => #
+#.##. => .
+#..## => .
+##### => #
+####. => #
+.##.# => #
+#.### => .
+...## => #
+.#.## => #
+#..#. => #
+#.#.. => #
+.###. => #
+##.## => #
+##..# => .
+.#... => #
+###.# => .
+..##. => .
+..... => .
+###.. => #
+..#.# => .
+.#..# => #
+##... => #
+#.... => .
+##.#. => .
+..#.. => #
+....# => .
+#...# => .
+#.#.# => #
+..### => .
+.#.#. => #
diff --git a/2018/day-12/plants.js b/2018/day-12/plants.js
@@ -0,0 +1,197 @@
+class Plants {
+  constructor (initial, rules) {
+    this.generations = []
+    this.boundaryBuffers = [0, 0]
+    this.rules = {}
+    if (rules && rules.length > 0) {
+      rules.forEach((rule) => {
+        this.addRule(rule)
+      })
+    }
+    this.boundaryBuffers = this.getBoundaryBuffers()
+    this._setInitialGeneration(initial)
+  }
+
+  _setInitialGeneration (initial) {
+    this.generations.push(
+      initial.split('').map((plant, idx) => {
+        return {
+          position: idx,
+          state: plant
+        }
+      })
+    )
+    this.generations[0] = this.pad(this.generations[0])
+  }
+
+  /**
+   * Adds a rule to the rules list
+   * @param {Object} rule {id: "..#..", generate: "#"}
+   * @returns {Object} Plants instance for chaining
+   */
+  addRule (rule) {
+    this.rules[rule.id] = rule.generate
+    return this // allow chaining
+  }
+
+  /**
+   * Determines the the pot state based on the pattern provided
+   * @param {String} pattern "..#.."
+   * @returns {String} "." or "#"
+   */
+  predictPlant (pattern) {
+    const result = this.rules[pattern] || '.'
+    return result
+  }
+
+  /**
+   * Advances the plants by one generation
+   * @returns {Array} The results of the new generation
+   */
+  advance () {
+    const prevGen = this.generations[this.generations.length - 1]
+
+    // Loop through all pots in the last generation to create a new generation
+    let nextGen = prevGen.map((pot) => {
+      // Assemble pattern for the given pot
+      let pattern = ''
+      for (let x = pot.position - 2; x <= pot.position + 2; x++) {
+        let pp = prevGen.find((p) => p.position === x)
+        pattern += (pp) ? pp.state : '.'
+      }
+      const state = this.predictPlant(pattern)
+
+      return {
+        position: pot.position,
+        state: state
+      }
+    })
+
+    nextGen = this.pad(nextGen)
+
+    // Store the new generation
+    this.generations.push(nextGen)
+    return this.generations[this.generations.length - 1]
+  }
+
+  /**
+   * Renders out a visual display of the pots in all generations
+   * Wrapper for getDisplay()
+   * @param {Number} start First pot to include
+   * @param {Number} end Last pot to include
+   */
+  display (start, end) {
+    console.log(this.getDisplay(start, end))
+  }
+
+  /**
+   * Scans the generations to find the leftmost and rightmost pot with a plant
+   * @returns {Array} [left, right] position of first and last pots
+   */
+  findPotBoundaries () {
+    return this.generations.reduce((acc, gen) => {
+      let pots = gen.filter((p) => p.state === '#')
+      return [
+        acc[0] < pots[0].position ? acc[0] : pots[0].position,
+        acc[1] < pots[pots.length - 1].postion ? acc[1] : pots[pots.length - 1].position
+      ]
+    }, [0, 0])
+  }
+
+  /**
+   * Rules need empty pots lef/right of row for verification. Figures out the number of pots we need
+   * to add to the left/right of a row
+   * @returns {Array} [left, right] necessary buffer size of first and last pots
+   */
+  getBoundaryBuffers () {
+    let buffers = [0, 0]
+    Object.keys(this.rules).filter((rule) => this.rules[rule] === '#').forEach((rule) => {
+      // For left edge
+      for (let x = 0; x < rule.length; x++) {
+        if (rule.substr(x, 1) === '.') {
+          let y = x + 1
+          buffers[0] = Math.max(buffers[0], y)
+        } else {
+          // break the loop when we encounter a #
+          x = rule.length
+          break
+        }
+      }
+
+      for (let x = rule.length - 1; x >= 0; x--) {
+        if (rule.substr(x, 1) === '.') {
+          let y = rule.length - x
+          buffers[1] = Math.max(buffers[1], y)
+        } else {
+          // break the loop when we encounter a #
+          x = -1
+          break
+        }
+      }
+    })
+    return buffers
+  }
+
+  /**
+   * Generates a visual display of the pots in all generations. Accepts optional boundaries.
+   * @param {Number} start First pot to include
+   * @param {Number} end Last pot to include.
+   */
+  getDisplay (start, end) {
+    // Find boundaries if not provided
+    if (!start || !end) {
+      const boundaries = this.findPotBoundaries()
+      start = start || boundaries[0] - 1
+      end = end || boundaries[1] + 1
+    }
+    let output = ''
+    this.generations.forEach((gen) => {
+      for (let p = start; p <= end; p++) {
+        const plant = gen.find((pot) => pot.position === p)
+        output += (plant) ? plant.state : '.'
+      }
+      output += '\n'
+    })
+    return output.trim()
+  }
+
+  /**
+   * Sums the number of plants present in all generations
+   */
+  getPlantTotal () {
+    return this.generations.reduce((gacc, g) => {
+      return gacc + g.filter((p) => p.state === '#').length
+    }, 0)
+  }
+
+  /**
+   * Generates a checksum calculated by summing the positions of all pots containing plants
+   * in a specified generation
+   * @param {Number} generation to generate checksum for
+   */
+  getCheckSum (generation) {
+    return this.generations[generation].filter((p) => p.state === '#')
+      .reduce((pacc, p) => pacc + p.position, 0)
+  }
+
+  /**
+   * Pads the generation to the left and right so the pots are present to support future generations
+   * @param {Array} generation List of pots representing a generation
+   * @returns generation list with extra pots
+   */
+  pad (generation) {
+    for (let x = 1; x <= this.boundaryBuffers[0]; x++) {
+      const first = generation[0].position
+      generation.splice(0, 0, { position: first - 1, state: '.' })
+    }
+    for (let x = 1; x <= this.boundaryBuffers[1]; x++) {
+      const last = generation[generation.length - 1].position
+      generation.push({ position: last + 1, state: '.' })
+    }
+    return generation
+  }
+}
+
+module.exports = {
+  Plants
+}