feat(2018 day-11): adds a way to find the max powered square without first generating cached tallies for every point

Author: developher-net

2018/day-11/fuel-cells.js

@@ -12,6 +12,7 @@ class Rack {
     if (typeof size === 'object' && size.length === 2) {
       this._allocateGrid(size)
     }
+    this.maxSquare = null
   }
 
   /**
@@ -89,10 +90,17 @@ class Rack {
 
   tallySquares (size) {
     this.cells = this.cells.map((cell, idx) => {
-      cell.squareTotal = this._tallySquare(idx, size)
+      cell.squareTotal = this._tallySquare(idx, size) || null
       return cell
     })
   }
+
+  findMaxSquare (size) {
+    return this.cells.reduce((acc, cell, idx) => {
+      let squarePower = this._tallySquare(idx, size)
+      return (squarePower !== null && squarePower > acc.power) ? { power: squarePower, idx: idx } : acc
+    }, { power: -99999, idx: -1 })
+  }
 }
 
 module.exports = {

2018/day-11/fuel-cells.test.js

@@ -98,4 +98,15 @@ describe('--- Day 11: Chronal Charge ---', () => {
       expect(actual).to.deep.equal(expected)
     })
   })
+  describe('findMaxSquare(size)', () => {
+    it('locates the top left corner of the square (of specified size) that has the maximum power in the grid', () => {
+      const expected = [21, 61]
+      const serial = 42
+      const gridSize = [300, 300]
+      const squareSize = [3, 3]
+      const grid = new Rack(serial, gridSize)
+      const actual = grid.cells[grid.findMaxSquare(squareSize).idx].coords
+      expect(actual).to.deep.equal(expected)
+    })
+  })
 })

2018/day-11/solution.js

@@ -5,17 +5,28 @@ const size = [300, 300]
 const squareSize = [3, 3]
 
 let powerBank = new Rack(serial, size)
-powerBank.tallySquares(squareSize)
-const answer = powerBank.getCellsByPower(squareSize)[0].coords
+// powerBank.tallySquares(squareSize)
+// const answer = powerBank.getCellsByPower(squareSize)[0].coords
+let max = powerBank.findMaxSquare(squareSize).idx
+const answer = powerBank.cells[max].coords
+
+console.log(`-- Part 1 --`)
+console.log(`Answer: ${answer}`)
 
 const anySizeSquares = []
 for (let dial = 1; dial <= 300; dial++) {
   console.log(`Measuring power with dial at ${dial}`)
-  powerBank.tallySquares([dial, dial])
-  let bestOfSizeX = powerBank.getCellsByPower(squareSize)[0]
+  // powerBank.tallySquares([dial, dial])
+  // let bestOfSizeX = powerBank.getCellsByPower(squareSize)[0]
+  // anySizeSquares.push({
+  //   coords: bestOfSizeX.coords,
+  //   power: bestOfSizeX.squareTotal,
+  //   size: dial
+  // })
+  const max = powerBank.findMaxSquare([dial, dial])
   anySizeSquares.push({
-    coords: bestOfSizeX.coords,
-    power: bestOfSizeX.squareTotal,
+    coords: powerBank.cells[max.idx].coords,
+    power: max.power,
     size: dial
   })
 }
@@ -24,7 +35,5 @@ const bestOfAnySize = anySizeSquares.sort(dynamicSort('-power'))[0]
 let answer2 = bestOfAnySize.coords
 answer2.push(bestOfAnySize.size)
 
-console.log(`-- Part 1 --`)
-console.log(`Answer: ${answer}`)
 console.log(`-- Part 2 --`)
 console.log(`Answer: ${answer2}`)