[TASK] Finished Day5

functions/src/day4.ts

@@ -8,7 +8,7 @@ class Day4 implements Day {
     const { drawnNumbers, bingoCards } = this.parseInput(input);
 
     // We are done as soon as we encounter the first bingo
-    return this.playBingo(drawnNumbers, bingoCards, _ => ({ isDone: true }) ).score;
+    return this.playBingo(drawnNumbers, bingoCards, () => ({ isDone: true }) ).score;
   }
 
   part2(input: string[]): number | string {

functions/src/day5.ts

@@ -0,0 +1,93 @@
+import Day from "./day";
+import Vector2 from "./vector2";
+
+class Day5 implements Day {
+
+  part1(input: string[]): number | string {
+
+    const vents = Day5.parseInput(input)
+      // For now, we should only consider purely horizontal or purely vertical vents:
+      .filter(v => v.start.x === v.end.x || v.start.y === v.end.y);
+
+    return Day5.countVentOverlaps(Day5.markVents(vents));
+  }
+
+  part2(input: string[]): number | string {
+
+    const vents = Day5.parseInput(input)
+    return Day5.countVentOverlaps(Day5.markVents(vents));
+  }
+
+  private static markVents(vents: Vent[]): Map<string, number> {
+    const grid = new Map<string, number>();
+    vents.forEach(v => Day5.markVent(v, grid));
+    return grid;
+  }
+
+  private static markVent(vent: Vent, grid: Map<string, number>) {
+
+    // Must be a diagonal line
+    const steps = Math.max(Math.abs(vent.end.x - vent.start.x), Math.abs(vent.end.y - vent.start.y));
+    const stepX = Day5.determineStep(vent.start.x, vent.end.x);
+    const stepY = Day5.determineStep(vent.start.y, vent.end.y);
+
+    for (let i = 0; i <= steps; i++) {
+      Day5.addVentPos(new Vector2(vent.start.x + stepX * i, vent.start.y + stepY * i), grid);
+    }
+  }
+
+  private static determineStep(start: number, end: number): number {
+    return start === end ? 0 : (start < end) ? 1 : -1;
+  }
+
+  private static countVentOverlaps(grid: Map<string, number>): number {
+
+    let count = 0;
+    for (const ventCount of grid.values()) {
+      if (ventCount >= 2) count++;
+    }
+
+    return count;
+  }
+
+  private static addVentPos(pos: Vector2, grid: Map<string, number>) {
+
+    const key = pos.key();
+    const existing = grid.get(key);
+    if (!existing) {
+      grid.set(key, 1);
+    } else {
+      grid.set(key, existing + 1);
+    }
+  }
+
+  private static parseInput(input: string[]): Vent[] {
+
+    const res: Vent[] = [];
+    for (const line of input) {
+      const startEnd = line.split(/\s*->\s*/);
+      res.push({
+        start: Vector2.parse(startEnd[0]),
+        end: Vector2.parse(startEnd[1])
+      });
+    }
+
+    return res;
+  }
+
+}
+
+class Vent {
+
+  readonly start: Vector2;
+  readonly end: Vector2;
+
+  constructor(start: Vector2, end: Vector2) {
+    this.start = start;
+    this.end = end;
+  }
+
+}
+
+
+export default Day5;

functions/src/index.ts

@@ -6,6 +6,7 @@ import Day1 from "./day1";
 import Day2 from "./day2";
 import Day3 from "./day3";
 import Day4 from "./day4";
+import Day5 from "./day5";
 
 
 // // Start writing Firebase Functions
@@ -26,6 +27,7 @@ export const day = {
   2: functions.region("europe-west1").https.onRequest((request, response) => { processDay(new Day2(), request, response) }),
   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) }),
 
 }
 

functions/src/vector2.ts

@@ -0,0 +1,23 @@
+
+class Vector2 {
+  readonly x: number;
+  readonly y: number;
+
+  constructor(x: number, y: number) {
+    this.x = x;
+    this.y = y;
+  }
+
+  static parse(input: string): Vector2 {
+    const splitIndex = input.indexOf(",");
+    const xString = input.substr(0, splitIndex);
+    const yString = input.substr(splitIndex + 1);
+    return new Vector2(parseInt(xString), parseInt(yString));
+  }
+
+  key(): string {
+    return `${this.x},${this.y}`;
+  }
+}
+
+export default Vector2;