feat(2018 day-14): eliminate the need to define elves when creating recipes

moves elves to be a property of recipes so a list of elves doesn't have to be manually defined

Breaks calculateXAfterY(x, y, elves), use calculateXAfterY(x, y) instead
Breaks findPattern('XXX', recipes, elves), use findPattern('XXX', recipes) instead
Breakds loopRecipesForElves(elves, recipes, X), use  loopRecipesForElves(recipes, 15) instead

Author: developher-net

2018/day-14/recipes.js

@@ -1,18 +1,37 @@
+class Elf {
+  constructor (location) {
+    this.location = location
+  }
+
+  move (distance) {
+    for (let x = 0; x < distance; x++) {
+      this.location = this.location.next
+    }
+  }
+}
+
 /**
  * Circular linked list of recipes
+ * @param {Array} recipes list of initial recipe values
  */
 class Recipes {
   constructor (recipes) {
     this.head = null
     this.tail = null
     this.length = 0
-    this.addFirst(recipes[0])
+    this.elves = []
+    this._addFirst(recipes[0])
     for (let x = 1; x < recipes.length; x++) {
       this.addRecipe(recipes[x])
     }
+    this.addElf(this.tail)
+    this.addElf(this.head)
   }
 
-  addFirst (recipe) {
+  /**
+   * @private
+   */
+  _addFirst (recipe) {
     const newRecipe = { value: recipe }
     newRecipe.next = newRecipe
     newRecipe.prev = newRecipe
@@ -22,6 +41,14 @@ class Recipes {
     return this
   }
 
+  /**
+   * Adds an elf (location marker) to the linked list for easier iterative tracking
+   * @param {*} location Item on the linked list that the elf is positioned at
+   */
+  addElf (location) {
+    this.elves.push(new Elf(location))
+  }
+
   /**
    * Adds a recipe to the linked list
    * @param {Number} recipe value
@@ -60,22 +87,18 @@ const totalDigitsInArray = (arr) => {
 
 /**
  * Loops the elves through the recipes list the specified number of times
- * @param {Array} elves list of elves
  * @param {LinkedList} recipes list of recipes
- * @param {Numbe} repeat count of desired iterations
+ * @param {Number} repeat count of desired iterations
  */
-const loopRecipesForElves = (elves, recipes, repeat) => {
+const loopRecipesForElves = (recipes, repeat) => {
   let result = ''
   for (let x = 1; x <= repeat; x++) {
-    const score = totalDigitsInArray(elves.map((elf) => elf.value))
+    const score = totalDigitsInArray(recipes.elves.map((elf) => elf.location.value))
     result += score.toString()
     recipes.scoreRecipes(score)
-    elves.forEach((elf, idx) => {
-      const distance = elf.value + 1
-      for (let x = 0; x < distance; x++) {
-        elf = elf.next
-      }
-      elves[idx] = elf
+    recipes.elves.forEach((elf, idx) => {
+      const distance = elf.location.value + 1
+      elf.move(distance)
     })
   }
   return result
@@ -84,21 +107,24 @@ const loopRecipesForElves = (elves, recipes, repeat) => {
 /**
  * Determines the next X recipes after the elves have generated Y recipes
  */
-const calculateXAfterY = (x, y, recipes, elves) => {
+const calculateXAfterY = (x, y, recipes) => {
   let iterator = recipes.head
-  while (recipes.length <= y) {
-    loopRecipesForElves(elves, recipes, 1)
+  let counter = recipes.length
+  while (counter < y) {
+    loopRecipesForElves(recipes, 1)
+    counter = recipes.length
   }
+  console.log(`${y} matches ${recipes.length}`)
 
-  if (recipes.length === y + 1) {
+  if (recipes.length === y) {
     iterator = recipes.head
-  } else {
+  } else if (recipes.length > y) {
     // In case multidigit recipe results created more than Y
     iterator = recipes.head.prev
   }
 
   while (recipes.length < x + y) {
-    loopRecipesForElves(elves, recipes, 1)
+    loopRecipesForElves(recipes, 1)
   }
 
   let result = ''
@@ -113,15 +139,14 @@ const calculateXAfterY = (x, y, recipes, elves) => {
  * Counts how many recipes are to the left of the specified pattern
  * @param {String} pattern to search for
  * @param {LinkedList} recipes recipe list
- * @param {Array} elves doing the work
  * @param {Number} bufferSize bucket size to search. Tuning bucket size can improve speed but may risk missing match if the match crosses buckets.
  */
-const findPattern = (pattern, recipes, elves, bufferSize) => {
+const findPattern = (pattern, recipes, bufferSize) => {
   bufferSize = bufferSize || 101
   let matched = false
   let position = recipes.length
   while (matched !== true) {
-    let haystack = loopRecipesForElves(elves, recipes, bufferSize)
+    let haystack = loopRecipesForElves(recipes, bufferSize)
     let offset = haystack.indexOf(pattern)
     if (offset > -1) {
       position += offset

2018/day-14/recipes.test.js

@@ -10,13 +10,9 @@ const {
 
 describe('--- Day 14: Chocolate Charts ---', () => {
   let recipes
-  let elves
   describe('Part 1:', () => {
     beforeEach(() => {
-      elves = [3, 7]
-      recipes = new Recipes(elves)
-      elves[0] = recipes.tail
-      elves[1] = recipes.head
+      recipes = new Recipes([3, 7])
     })
     describe('new Recipes()', () => {
       it('builds a linked list', () => {
@@ -54,12 +50,10 @@ describe('--- Day 14: Chocolate Charts ---', () => {
     describe('loopRecipeForEleves()', () => {
       it('loops through the recipe object for the specified elves the specified number of times', () => {
         const expected = '37101012451589167792' // list of recipe values in the last iteration of the example
-        let actual = ''
-
-        loopRecipesForElves(elves, recipes, 15)
 
+        loopRecipesForElves(recipes, 15)
+        let actual = recipes.tail.value.toString()
         let iterator = recipes.tail.next
-        actual += recipes.tail.value.toString()
         while (iterator !== recipes.tail) {
           actual += iterator.value.toString()
           iterator = iterator.next
@@ -68,45 +62,49 @@ describe('--- Day 14: Chocolate Charts ---', () => {
         expect(expected).to.equal(actual)
       })
     })
-    describe('calculateXAfterY(x, y, recipe, elves)', () => {
+    describe('calculateXAfterY(x, y, recipe)', () => {
       it('predicts the next X results after the elves have executed Y', () => {
-        let actual = calculateXAfterY(10, 9, recipes, elves)
+        let actual = calculateXAfterY(10, 9, recipes)
         expect(actual).to.equal('5158916779')
       })
       it('predicts the next X results after the elves have executed Y', () => {
-        const actual = calculateXAfterY(10, 5, recipes, elves)
+        const actual = calculateXAfterY(10, 5, recipes)
         expect(actual).to.equal('0124515891')
       })
       it('predicts the next X results after the elves have executed Y', () => {
-        const actual = calculateXAfterY(10, 18, recipes, elves)
+        const actual = calculateXAfterY(10, 18, recipes)
         expect(actual).to.equal('9251071085')
       })
       it('predicts the next X results after the elves have executed Y', () => {
-        const actual = calculateXAfterY(10, 2018, recipes, elves)
+        const actual = calculateXAfterY(10, 2018, recipes)
         expect(actual).to.equal('5941429882')
       })
+      it('positions results correctly if X triggers 2 recipes being added', () => {
+        let actual = calculateXAfterY(3, 15, recipes)
+        expect(actual).to.equal('677')
+      })
     })
     describe('findPattern()', () => {
       it('counts the number of recipes to the left of the specified pattern', () => {
-        const actual = findPattern('51589', recipes, elves)
+        const actual = findPattern('51589', recipes)
         expect(actual).to.equal(9)
       })
     })
     describe('findPattern()', () => {
       it('counts the number of recipes to the left of the specified pattern', () => {
-        const actual = findPattern('01245', recipes, elves)
+        const actual = findPattern('01245', recipes)
         expect(actual).to.equal(5)
       })
     })
     describe('findPattern()', () => {
       it('counts the number of recipes to the left of the specified pattern', () => {
-        const actual = findPattern('92510', recipes, elves)
+        const actual = findPattern('92510', recipes)
         expect(actual).to.equal(18)
       })
     })
     describe('findPattern()', () => {
       it('counts the number of recipes to the left of the specified pattern', () => {
-        const actual = findPattern('59414', recipes, elves)
+        const actual = findPattern('59414', recipes)
         expect(actual).to.equal(2018)
       })
     })

2018/day-14/solution.js

@@ -6,12 +6,9 @@ const {
 
 const input = 540561
 
-let elves = [3, 7]
-let recipes = new Recipes(elves)
-elves[0] = recipes.tail
-elves[1] = recipes.head
+let recipes = new Recipes([3, 7])
 
-const answer = calculateXAfterY(10, input, recipes, elves)
+const answer = calculateXAfterY(10, input, recipes)
 
 console.log(`-- Part 1 --`)
 console.log(`Answer: ${answer}`)