feat(2018 day-11): Finds the square with the most power

Author: developher-net

2018/day-11/fuel-cells.js

@@ -1,3 +1,5 @@
+const { dynamicSort } = require('../day-04/helpers')
+
 class Rack {
   /**
    * Initializes a new power rack
@@ -30,6 +32,10 @@ class Rack {
     }
   }
 
+  getCellsByPower () {
+    return this.cells.sort(dynamicSort('-squareTotal'))
+  }
+
   /**
    * Calculates the Rack ID at the specified coordinate
    * @param {Array} coords [x,y]
@@ -57,14 +63,18 @@ class Rack {
 
   _tallySquare (idx, size) {
     let power = 0
+    let valid = true
     for (let x = 0; x < size[0]; x++) {
       for (let y = 0; y < size[0]; y++) {
         let pointer = idx + x + (y * this.size[0])
         let dest = this.cells[pointer]
+        valid = (dest) ? valid : false // flag invalid results from cells off the grid
         power += (dest) ? dest.power : 0
       }
     }
-    return power
+
+    // Discard value if square exceeds the grid
+    return (valid) ? power : null
   }
 
   tallySquares (size) {

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

@@ -76,4 +76,26 @@ describe('--- Day 11: Chronal Charge ---', () => {
       expect(actual).to.equal(expected)
     })
   })
+  describe('getCellsByPower()', () => {
+    it('sorts the cells by their available square power, skipping ones that go off the edge of the rack', () => {
+      const expected = [33, 45]
+      const serial = 18
+      const gridSize = [300, 300]
+      const squareSize = [3, 3]
+      const grid = new Rack(serial, gridSize)
+      grid.tallySquares(squareSize)
+      const actual = grid.getCellsByPower(squareSize)[0].coords
+      expect(actual).to.deep.equal(expected)
+    })
+    it('sorts the cells by their available square power, skipping ones that go off the edge of the rack', () => {
+      const expected = [21, 61]
+      const serial = 42
+      const gridSize = [300, 300]
+      const squareSize = [3, 3]
+      const grid = new Rack(serial, gridSize)
+      grid.tallySquares(squareSize)
+      const actual = grid.getCellsByPower(squareSize)[0].coords
+      expect(actual).to.deep.equal(expected)
+    })
+  })
 })

2018/day-11/solution.js

@@ -1,6 +1,13 @@
 const { Rack } = require('./fuel-cells')
 const serial = 1133 // From puzzle input
+const size = [300, 300]
+const squareSize = [3, 3]
 
-let powerBank = new Rack(serial)
-
-console.log(powerBank)
+let powerBank = new Rack(serial, size)
+powerBank.tallySquares(squareSize)
+const answer = powerBank.getCellsByPower(squareSize)[0].coords
+const answer2 = ''
+console.log(`-- Part 1 --`)
+console.log(`Answer: ${answer}`)
+console.log(`-- Part 2 --`)
+console.log(`Answer: ${answer2}`)