[TASK] Implemented Day 6

functions/src/day6.ts

@@ -0,0 +1,35 @@
+import Day from "./day";
+import Utils from "./utils";
+
+class Day6 implements Day {
+
+  part1(input: string[]): number | string {
+
+    const initial = input[0].split(",").map(s => parseInt(s));
+    return this.countFishAfter(initial, 80).toString(10);
+  }
+
+  part2(input: string[]): number | string {
+
+    const initial = input[0].split(",").map(s => parseInt(s));
+    return this.countFishAfter(initial, 256).toString(10);
+  }
+
+  countFishAfter(initial: number[], days: number): bigint {
+
+    // We represent the data as the number of glowfish in a specific state per day, then we can just shift that array around:
+    const fishStates = Array(9).fill(0n);
+    initial.forEach(f => fishStates[f]++);
+
+    for (let i = 0; i < days; i++) {
+      const reproducingFish = fishStates.shift()
+      fishStates[6] += reproducingFish;
+      fishStates.push(reproducingFish);
+    }
+
+    return Utils.bigSum(fishStates);
+  }
+
+}
+
+export default Day6;

functions/src/index.ts

@@ -7,6 +7,7 @@ import Day2 from "./day2";
 import Day3 from "./day3";
 import Day4 from "./day4";
 import Day5 from "./day5";
+import Day6 from "./day6";
 
 
 // // Start writing Firebase Functions
@@ -28,6 +29,7 @@ export const day = {
   3: functions.region("europe-west1").https.onRequest((request, response) => { processDay(new Day3(), request, response) }),
   4: functions.region("europe-west1").https.onRequest((request, response) => { processDay(new Day4(), request, response) }),
   5: functions.region("europe-west1").https.onRequest((request, response) => { processDay(new Day5(), request, response) }),
+  6: functions.region("europe-west1").https.onRequest((request, response) => { processDay(new Day6(), request, response) }),
 
 }
 

functions/src/utils.ts

@@ -14,7 +14,11 @@ class Utils {
   }
 
   static sum(values: number[]): number {
-    return values.reduce((a, b) => a + b, 0);
+    return values.reduce((a, b) => a + b);
+  }
+
+  static bigSum(values: bigint[]): bigint {
+    return values.reduce((a, b) => a + b);
   }
 
   static zeroes(length: number): number[] {

functions/tsconfig.json

@@ -6,7 +6,7 @@
     "outDir": "lib",
     "sourceMap": true,
     "strict": true,
-    "target": "es2017"
+    "target": "es2020"
   },
   "compileOnSave": true,
   "include": [