feat: day 6 (#8)

* wildcard for workspace members

* day 6 part 1

* use trim

* ignore vscode dir

* count the array

* day 6 part 2

.gitignore

@@ -1,2 +1,3 @@
 deno.lock
 **/input.txt
+.vscode

day1/mod.ts

@@ -1,10 +1,8 @@
 export function parse(data: string): number[][] {
-  const parsed = data.split("\n").map((x) =>
+  const parsed = data.trim().split("\n").map((x) =>
     x.split(" ").map((x) => parseInt(x))
   );
   return parsed
-    // Remove the last element, which is an empty string
-    .slice(0, parsed.length - 1)
     // Three spaces are used to separate the numbers
     .map((x) => [x[0], x[3]]);
 }

day2/mod.ts

@@ -1,10 +1,7 @@
 export function parse(data: string): number[][] {
-  const parsed = data.split("\n").map((x) =>
+  return data.trim().split("\n").map((x) =>
     x.split(" ").map((x) => parseInt(x))
   );
-  return parsed
-    // Remove the last element, which is an empty string
-    .slice(0, parsed.length - 1);
 }
 
 function is_safe(report: number[]): boolean {

day4/mod.ts

@@ -2,10 +2,7 @@ const XMAS: string = "XMAS";
 const MAS: string = "MAS";
 
 export function parse(data: string): string[] {
-  const parsed = data.split("\n");
-  return parsed
-    // Remove the last element, which is an empty string
-    .slice(0, parsed.length - 1);
+  return data.trim().split("\n");
 }
 
 class Grid {

day5/mod.ts

@@ -154,9 +154,8 @@ class DirectedGraph {
   }
 }
 
-export function parse(data_r: string): [number[][], number[][]] {
-  const data = data_r.trim();
-  const [rules_s, pages_s, _] = data.split("\n\n");
+export function parse(data: string): [number[][], number[][]] {
+  const [rules_s, pages_s, _] = data.trim().split("\n\n");
   const rules = rules_s.split("\n").map((rule) =>
     rule.split("|").map((r) => Number(r))
   );

day6/deno.json

@@ -0,0 +1,7 @@
+{
+  "name": "@scope/day6",
+  "version": "0.1.0",
+  "exports": {
+    ".": "./mod.ts"
+  }
+}

day6/example.txt

@@ -0,0 +1,10 @@
+....#.....
+.........#
+..........
+..#.......
+.......#..
+..........
+.#..^.....
+........#.
+#.........
+......#...

day6/mod.ts

@@ -0,0 +1,164 @@
+class Grid {
+  data: string[][];
+  guard: [number, number];
+  guardDirection: [number, number];
+
+  constructor(data: string[][]) {
+    this.data = data;
+    this.guard = this.findGuard;
+    this.guardDirection = [0, -1];
+  }
+
+  get width(): number {
+    return this.data[0].length;
+  }
+
+  get height(): number {
+    return this.data.length;
+  }
+
+  inside(x: number, y: number): boolean {
+    return x >= 0 && x < this.width && y >= 0 && y < this.height;
+  }
+
+  get(x: number, y: number): string {
+    if (this.inside(x, y)) {
+      return this.data[y][x];
+    } else {
+      return "";
+    }
+  }
+
+  set(x: number, y: number, value: string) {
+    if (this.inside(x, y)) {
+      this.data[y][x] = value;
+    }
+  }
+
+  get findGuard(): [number, number] {
+    for (let y = 0; y < this.height; y++) {
+      for (let x = 0; x < this.width; x++) {
+        if (this.get(x, y) === "^") {
+          return [x, y];
+        }
+      }
+    }
+    return [-1, -1];
+  }
+
+  isWall(x: number, y: number): boolean {
+    return this.get(x, y) === "#";
+  }
+
+  isVisited(x: number, y: number): boolean {
+    return this.get(x, y) === "X";
+  }
+
+  changeDirection() {
+    // [0, -1] -> [1, 0] -> [0, 1] -> [-1, 0] -> [0, -1]
+    const [x, y] = this.guardDirection;
+    this.guardDirection = [-y, x];
+  }
+
+  guardPresent(): boolean {
+    const [x, y] = this.guard;
+    return this.inside(x, y);
+  }
+
+  guardWalk() {
+    const [x, y] = this.guard;
+    const [dx, dy] = this.guardDirection;
+
+    const [x_, y_] = [x + dx, y + dy];
+
+    if (this.isWall(x_, y_)) {
+      this.changeDirection();
+      this.guardWalk();
+    } else {
+      this.guard = [x_, y_];
+      {
+        this.set(x, y, "X");
+        this.set(x_, y_, "^");
+      }
+    }
+  }
+
+  addObstacle(x: number, y: number) {
+    this.set(x, y, "#");
+  }
+
+  x_locations(): number[][] {
+    const locations = [];
+    for (let y = 0; y < this.height; y++) {
+      for (let x = 0; x < this.width; x++) {
+        if (this.isVisited(x, y)) {
+          locations.push([x, y]);
+        }
+      }
+    }
+    return locations;
+  }
+}
+
+function clone(data: string[][]): string[][] {
+  return data.map((row) => {
+    return row.slice();
+  });
+}
+
+export function parse(data_r: string): string[][] {
+  const data = data_r.trim();
+  return data.split("\n").map((line) => {
+    return line.split("");
+  });
+}
+
+export function solve1(data: string[][]): number {
+  const grid = new Grid(clone(data));
+
+  while (true) {
+    grid.guardWalk();
+    if (!grid.guardPresent()) {
+      break;
+    }
+  }
+
+  return grid.x_locations().length;
+}
+
+export function solve2(data: string[][]): number {
+  const grid = new Grid(clone(data));
+
+  while (true) {
+    grid.guardWalk();
+    if (!grid.guardPresent()) {
+      break;
+    }
+  }
+
+  const locations = grid.x_locations();
+
+  return locations.filter(([x, y]) => {
+    const grid = new Grid(clone(data));
+    grid.addObstacle(x, y);
+    let stepCount = 0;
+    while (true) {
+      grid.guardWalk();
+      if (!grid.guardPresent()) {
+        break;
+      }
+      stepCount++;
+      if (stepCount > 2 * locations.length) {
+        return true;
+      }
+    }
+    return false;
+  }).length;
+}
+
+if (import.meta.main) {
+  const data_path = new URL("input.txt", import.meta.url).pathname;
+  const data = parse(await Deno.readTextFile(data_path));
+  console.log(solve1(data));
+  console.log(solve2(data));
+}

day6/test.ts

@@ -0,0 +1,9 @@
+import { assertEquals } from "@std/assert";
+import { parse, solve1, solve2 } from "./mod.ts";
+
+Deno.test(async function testExample() {
+  const example_data_path = new URL("example.txt", import.meta.url).pathname;
+  const example_data = parse(await Deno.readTextFile(example_data_path));
+  assertEquals(solve1(example_data), 41);
+  assertEquals(solve2(example_data), 6);
+});

deno.json

@@ -1,13 +1,5 @@
 {
-  "workspace": {
-    "members": [
-      "./day1",
-      "./day2",
-      "./day3",
-      "./day4",
-      "./day5"
-    ]
-  },
+  "workspace": ["./day*"],
   "imports": {
     "@std/assert": "jsr:@std/assert@1"
   }