Day 12

Author: stevenhorsman

day-11-chronal-change/test.js

@@ -2,7 +2,7 @@ const expect = require('chai').expect;
 
 const fuelcells = require('./fuelcells');
 
-describe.only('Day 11: Chronal Charge', () => {
+describe('Day 11: Chronal Charge', () => {
 
   describe('Calculate fuel cell value', () => {
     it('fuel cell at 3,5 in a grid with serial number 8', () => {

day-12-subterranean-sustainability/input.txt

@@ -0,0 +1,34 @@
+initial state: ###.......##....#.#.#..###.##..##.....#....#.#.....##.###...###.#...###.###.#.###...#.####.##.#....#
+
+..... => .
+#..## => .
+..### => #
+..#.# => #
+.#.#. => .
+####. => .
+##.## => #
+#.... => .
+#...# => .
+...## => .
+##..# => .
+.###. => #
+##### => #
+#.#.. => #
+.##.. => #
+.#.## => .
+...#. => #
+#.##. => #
+..#.. => #
+##... => #
+....# => .
+###.# => #
+#..#. => #
+#.### => #
+##.#. => .
+###.. => #
+.#### => .
+.#... => #
+..##. => .
+.##.# => .
+#.#.# => #
+.#..# => .

day-12-subterranean-sustainability/plants.js

@@ -0,0 +1,86 @@
+class Transformation {
+  constructor(matcher, result) {
+    this.matcher = matcher;
+    this.result = result;
+  }
+}
+
+class State {
+  constructor(initialState, firstIndex =-2) {
+    //TODO - optimise and only add if nothing at the end
+    this.current = initialState;
+    this.firstIndex = firstIndex + 2;
+    if (!this.current.startsWith('....')) {
+      this.current = '....' + this.current;
+      this.firstIndex = this.firstIndex - 4;
+    }
+
+    if (!this.current.endsWith('....')) {
+      this.current = this.current + '....';
+    }
+  }
+
+  evolve(transformations) {
+    let nextString = '';
+    //console.log('currLEngth:',this.current.length - 4);
+    for(let i = 0; i <this.current.length - 4; i++) {
+      let replacementChar = '.';
+      transformations.forEach((transformation) => {
+        if (this.current.substring(i,i+5) === transformation.matcher) {
+          //console.log(this.current.substring(i,i+5),'matches',transformation.matcher);
+          replacementChar = transformation.result;
+        }
+      });
+      //console.log(i,'replacementChar',replacementChar);
+      nextString = nextString + replacementChar;
+    }
+    //console.log('next String',nextString);
+    return new State(nextString, this.firstIndex);
+  }
+
+  calculateSum() {
+    let sum = 0;
+    for(let i = 0; i <this.current.length; i++) {
+      if (this.current.charAt(i) == '#') {
+        //console.log('Adding',i+this.firstIndex);
+        sum += i+this.firstIndex;
+      }
+    }
+    return sum;
+  }
+}
+
+function calculateSum(input, iterations = 20) {
+  let inputLines = input.split(/\r?\n/);
+  let state = parseInitialState(inputLines.shift());
+  inputLines.shift();
+
+  let transformations = [];
+  inputLines
+    .map((line) => {
+    let result = line.trim().match(/(.+) => (.+)/);
+    transformations.push(new Transformation(result[1],result[2]));
+  });
+
+  let actualIt = iterations;
+  if (iterations > 1000) {
+    iterations = 1000;
+  }
+  for(let i=0;i<iterations;i++) {
+    state = state.evolve(transformations);
+  }
+
+  if (actualIt > 1000) {
+    let currSum = state.calculateSum();
+    let diff = state.evolve(transformations).calculateSum() - currSum;
+    return (actualIt - iterations) * diff + currSum;
+  }
+
+  return state.calculateSum();
+}
+
+function parseInitialState(input) {
+  return new State(input.replace('initial state: ',''));
+}
+
+module.exports.calculateSum = calculateSum;

day-12-subterranean-sustainability/test.js

@@ -0,0 +1,42 @@
+const expect = require('chai').expect;
+const fs = require('fs');
+
+const plants = require('./plants');
+
+describe('Day 12: Subterranean Sustainability', () => {
+    
+  describe('Part One', () => {
+    it('should calculate the sum of all pots after 20 iterations', () => {
+      const input = 
+      `initial state: #..#.#..##......###...###
+
+        ...## => #
+        ..#.. => #
+        .#... => #
+        .#.#. => #
+        .#.## => #
+        .##.. => #
+        .#### => #
+        #.#.# => #
+        #.### => #
+        ##.#. => #
+        ##.## => #
+        ###.. => #
+        ###.# => #
+        ####. => #`;
+      expect(plants.calculateSum(input)).to.equal(325);
+    });
+
+    it('Input file should return after 20 iterations', () => {
+      const input = fs.readFileSync('day-12-subterranean-sustainability/input.txt').toString();
+      expect(plants.calculateSum(input)).to.equal(3221);
+    });
+  });
+
+  describe('Part Two', () => {
+    it('Input file should return after 50000000000 iterations', () => {
+      const input = fs.readFileSync('day-12-subterranean-sustainability/input.txt').toString();
+      expect(plants.calculateSum(input,50000000000)).to.equal(2600000001872);
+    });
+  });
+});