feat(2020-day-07): recursively find all bag colors that allow specified child bag

Author: developher-net

2020/day-7/bagRules.js

@@ -8,7 +8,9 @@ const parseRule = (rule) => {
     result.inner = outRemainder[0].split(', ').map((str) => {
       const inRemainder = str.split(' ')
       const count = Number(inRemainder.shift())
-      const color = inRemainder.join(' ').replace('s.', '')
+      const color = inRemainder.join(' ')
+        .replace('.', '')
+        .replace('bags', 'bag')
       return {
         count,
         color
@@ -19,6 +21,34 @@ const parseRule = (rule) => {
   return result
 }
 
+const findAllowedOuter = (rules, color) => {
+  const allowed = {}
+
+  // Loop through the rules, find all colors this bag is allowed within
+  rules.filter((rule) => {
+    // console.debug(rule)
+    if (!rule.inner) { return false }
+    // match when inners contain the color
+    return (
+      rule.inner &&
+      rule.inner.filter((child) => {
+        return (child.color === color)
+      }).length > 0
+    )
+  }).forEach((rule) => {
+    allowed[rule.outer] = true
+  })
+
+  // Take the list of allowed colors, and find out which they are allowed within
+  Object.keys(allowed).forEach((color) => {
+    // Recursively loop
+    Object.assign(allowed, findAllowedOuter(rules, color))
+  })
+
+  return allowed
+}
+
 module.exports = {
-  parseRule
+  parseRule,
+  findAllowedOuter
 }

2020/day-7/bagRules.test.js

@@ -1,6 +1,6 @@
 /* eslint-env mocha */
 const { expect } = require('chai')
-const { parseRule } = require('./bagRules')
+const { parseRule, findAllowedOuter } = require('./bagRules')
 
 const testData = {
   rules: [
@@ -39,5 +39,23 @@ describe('--- Day 7: Handy Haversacks ---', () => {
         })
       })
     })
+    describe('findAllowedOuter()', () => {
+      it('list bags the specified bag is allowed to be placed in', () => {
+        const expectedColors = [
+          'bright white bag',
+          'muted yellow bag',
+          'dark orange bag',
+          'light red bag'
+        ]
+        const result = findAllowedOuter(
+          testData.rules.map(parseRule),
+          'shiny gold bag'
+        )
+        expectedColors.forEach(color => {
+          expect(result[color]).to.equal(true)
+        })
+        expect(Object.keys(result).length).to.equal(expectedColors.length)
+      })
+    })
   })
 })