From 95772849e410b530032d8f4b6bd49e01d62ca06f Mon Sep 17 00:00:00 2001
From: Bas Dado <bas@gametailors.com>
Date: Tue, 7 Dec 2021 20:01:39 +0100
Subject: [PATCH] [TASK] Implemented Day 6

---
 functions/src/day6.ts    | 35 +++++++++++++++++++++++++++++++++++
 functions/src/index.ts   |  2 ++
 functions/src/utils.ts   |  6 +++++-
 functions/tsconfig.json  |  2 +-
 input/day/6-example.http |  6 ++++++
 input/day/6.http         |  6 ++++++
 6 files changed, 55 insertions(+), 2 deletions(-)
 create mode 100644 functions/src/day6.ts
 create mode 100644 input/day/6-example.http
 create mode 100644 input/day/6.http

diff --git a/functions/src/day6.ts b/functions/src/day6.ts
new file mode 100644
index 0000000..575f13f
--- /dev/null
+++ b/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;
\ No newline at end of file
diff --git a/functions/src/index.ts b/functions/src/index.ts
index a50ae52..81dc461 100644
--- a/functions/src/index.ts
+++ b/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) }),
 
 }
 
diff --git a/functions/src/utils.ts b/functions/src/utils.ts
index b85f13c..3c81a3f 100644
--- a/functions/src/utils.ts
+++ b/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[] {
diff --git a/functions/tsconfig.json b/functions/tsconfig.json
index 7ce05d0..f40bec8 100644
--- a/functions/tsconfig.json
+++ b/functions/tsconfig.json
@@ -6,7 +6,7 @@
     "outDir": "lib",
     "sourceMap": true,
     "strict": true,
-    "target": "es2017"
+    "target": "es2020"
   },
   "compileOnSave": true,
   "include": [
diff --git a/input/day/6-example.http b/input/day/6-example.http
new file mode 100644
index 0000000..248d7ae
--- /dev/null
+++ b/input/day/6-example.http
@@ -0,0 +1,6 @@
+POST http://localhost:5001/advent-of-code-2021-911a8/europe-west1/day-6
+Content-Type: text/plain
+
+3,4,3,1,2
+
+###
diff --git a/input/day/6.http b/input/day/6.http
new file mode 100644
index 0000000..b7176b6
--- /dev/null
+++ b/input/day/6.http
@@ -0,0 +1,6 @@
+POST http://localhost:5001/advent-of-code-2021-911a8/europe-west1/day-6
+Content-Type: text/plain
+
+3,3,2,1,4,1,1,2,3,1,1,2,1,2,1,1,1,1,1,1,4,1,1,5,2,1,1,2,1,1,1,3,5,1,5,5,1,1,1,1,3,1,1,3,2,1,1,1,1,1,1,4,1,1,1,1,1,1,1,4,1,3,3,1,1,3,1,3,1,2,1,3,1,1,4,1,2,4,4,5,1,1,1,1,1,1,4,1,5,1,1,5,1,1,3,3,1,3,2,5,2,4,1,4,1,2,4,5,1,1,5,1,1,1,4,1,1,5,2,1,1,5,1,1,1,5,1,1,1,1,1,3,1,5,3,2,1,1,2,2,1,2,1,1,5,1,1,4,5,1,4,3,1,1,1,1,1,1,5,1,1,1,5,2,1,1,1,5,1,1,1,4,4,2,1,1,1,1,1,1,1,3,1,1,4,4,1,4,1,1,5,3,1,1,1,5,2,2,4,2,1,1,3,1,5,5,1,1,1,4,1,5,1,1,1,4,3,3,3,1,3,1,5,1,4,2,1,1,5,1,1,1,5,5,1,1,2,1,1,1,3,1,1,1,2,3,1,2,2,3,1,3,1,1,4,1,1,2,1,1,1,1,3,5,1,1,2,1,1,1,4,1,1,1,1,1,2,4,1,1,5,3,1,1,1,2,2,2,1,5,1,3,5,3,1,1,4,1,1,4
+
+###