feat(2021-day-03): calculate engine's power consumption for part 1

Author: developher-net

2021/day-03/engineDiagnostics.js

@@ -0,0 +1,53 @@
+/**
+ * Find the most common bit at a position
+ * @param [str] data
+ * @param int position
+ */
+const getMostCommon = (data, position) => {
+  const offs = data.filter((reading) => {
+    return reading[position] === '0'
+  }).length
+  // there can only be 2 values, so easy to check which has more as being 50% or above
+  return (offs >= data.length / 2) ? '0' : '1'
+}
+
+/**
+ * Find the least common bit at a position
+ * @param [str] data
+ * @param int position
+ */
+const getLeastCommon = (data, position) => {
+  return (getMostCommon(data, position) === '0') ? '1' : '0'
+}
+
+/**
+ * Calc the gamma value of the data set
+ * @param [str] data
+ */
+const getGamma = (data) => {
+  let gamma = ''
+  for (let x = 0; x < data[0].length; x++) {
+    gamma += getMostCommon(data, x)
+  }
+  return gamma
+}
+
+const getEpsilon = (data) => {
+  let epsilon = ''
+  for (let x = 0; x < data[0].length; x++) {
+    epsilon += getLeastCommon(data, x)
+  }
+  return epsilon
+}
+
+const calcPowerConsumption = (gamma, epsilon) => {
+  return parseInt(gamma, 2) * parseInt(epsilon, 2)
+}
+
+module.exports = {
+  getGamma,
+  getEpsilon,
+  getMostCommon,
+  getLeastCommon,
+  calcPowerConsumption
+}

2021/day-03/engineDiagnostics.test.js

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+/* eslint-env mocha */
+const { expect } = require('chai')
+const { getMostCommon, getLeastCommon, getEpsilon, getGamma, calcPowerConsumption } = require('./engineDiagnostics')
+
+const testData = [
+  '00100',
+  '11110',
+  '10110',
+  '10111',
+  '10101',
+  '01111',
+  '00111',
+  '11100',
+  '10000',
+  '11001',
+  '00010',
+  '01010'
+]
+
+describe('--- Day 3: Binary Diagnostic ---', () => {
+  describe('Part 1', () => {
+    describe('getMostCommon()', () => {
+      it('finds the most common bit at a position', () => {
+        expect(getMostCommon(testData, 0)).to.equal('1')
+        expect(getMostCommon(testData, 1)).to.equal('0')
+        expect(getMostCommon(testData, 2)).to.equal('1')
+        expect(getMostCommon(testData, 3)).to.equal('1')
+        expect(getMostCommon(testData, 4)).to.equal('0')
+      })
+    })
+    describe('getLeastCommon()', () => {
+      it('finds the least common bit at a position', () => {
+        expect(getLeastCommon(testData, 0)).to.equal('0')
+        expect(getLeastCommon(testData, 1)).to.equal('1')
+        expect(getLeastCommon(testData, 2)).to.equal('0')
+        expect(getLeastCommon(testData, 3)).to.equal('0')
+        expect(getLeastCommon(testData, 4)).to.equal('1')
+      })
+    })
+    describe('getGamma()', () => {
+      it('finds the gamma rate from the provided data using the most common bits in each position', () => {
+        expect(getGamma(testData)).to.equal('10110')
+      })
+    })
+    describe('getEpsilon()', () => {
+      it('finds the epsilon rate from the provided data using the least common bits in each position', () => {
+        expect(getEpsilon(testData)).to.equal('01001')
+      })
+    })
+    describe('calcPowerConsumption', () => {
+      it('calculates the power consumption by multiplying the gamma and epsilon rates as decimals', () => {
+        expect(calcPowerConsumption('10110', '01001')).to.equal(198)
+      })
+    })
+  })
+})

2021/day-03/index.js

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+// eslint-disable-next-line no-unused-vars
+const console = require('../helpers')
+require('./solution')