feat(day_2): both exercises done

README.md

@@ -5,3 +5,4 @@
 | Day | Name            | Part 1 | Part 2 |
 | :-: | :-------------- | :----: | :----: |
 |  1  | Secret Entrance |   ⭐   |   ⭐   |
+|  2  | Gift Shop       |   ⭐   |   ⭐   |

src/__tests__/day_2_test.ts

@@ -0,0 +1,20 @@
+import { assertEquals } from "@std/assert";
+import {
+  count_invalid_ids_sum,
+  count_new_invalid_ids_sum,
+  read_id_ranges,
+} from "../exercises/day_2.ts";
+
+const FILE_PATH = "src/exercises/assets/day_2_test_input.txt";
+
+Deno.test("Day 2 - A", async () => {
+  const id_ranges = await read_id_ranges(FILE_PATH);
+  const invalid_sum = count_invalid_ids_sum(id_ranges);
+  assertEquals(invalid_sum, 1227775554);
+});
+
+Deno.test("Day 2 - B", async () => {
+  const id_ranges = await read_id_ranges(FILE_PATH);
+  const invalid_sum = count_new_invalid_ids_sum(id_ranges);
+  assertEquals(invalid_sum, 4174379265);
+});

src/exercises/assets/day_2_input.txt

@@ -0,0 +1 @@
+385350926-385403705,48047-60838,6328350434-6328506208,638913-698668,850292-870981,656-1074,742552-796850,4457-6851,138-206,4644076-4851885,3298025-3353031,8594410816-8594543341,396-498,1558-2274,888446-916096,12101205-12154422,2323146444-2323289192,37-57,101-137,46550018-46679958,79-96,317592-341913,495310-629360,33246-46690,14711-22848,1-17,2850-4167,3723700171-3723785996,190169-242137,272559-298768,275-365,7697-11193,61-78,75373-110112,425397-451337,9796507-9899607,991845-1013464,77531934-77616074

src/exercises/assets/day_2_test_input.txt

@@ -0,0 +1 @@
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124

src/exercises/day_2.ts

@@ -0,0 +1,95 @@
+interface Range {
+  init: number;
+  end: number;
+}
+
+export default async function GiftShop() {
+  const input_ranges = await read_id_ranges(
+    "src/exercises/assets/day_2_input.txt",
+  );
+  const invalid_id_count = count_invalid_ids_sum(input_ranges);
+  const new_invalid_id_count = count_new_invalid_ids_sum(input_ranges);
+  console.log(">> Invalid id count: ", invalid_id_count, new_invalid_id_count);
+}
+
+// Repeating numbers are the invalid ids
+// Leading zeroes are invalid ids
+export function count_invalid_ids_sum(id_ranges: Range[]): number {
+  let invalid_id_sum: number = 0;
+  id_ranges.forEach((range) => {
+    for (let i = range.init; i <= range.end; i++) {
+      if (is_id_mirror(i)) {
+        invalid_id_sum += i;
+      }
+    }
+  });
+  return invalid_id_sum;
+}
+
+export function count_new_invalid_ids_sum(id_ranges: Range[]): number {
+  let invalid_id_sum: number = 0;
+  id_ranges.forEach((range) => {
+    for (let i = range.init; i <= range.end; i++) {
+      if (is_id_repeating(i)) {
+        invalid_id_sum += i;
+      }
+    }
+  });
+  return invalid_id_sum;
+}
+
+function is_id_repeating(id: number): boolean {
+  const str_id = id.toString();
+
+  if (str_id[0] === "0") {
+    return false;
+  }
+
+  for (let size = 1; size <= str_id.length / 2; size++) {
+    const baselise_slice: string = str_id.slice(0, size);
+
+    if (str_id.length % size !== 0) {
+      continue;
+    }
+
+    let is_repeating = true;
+
+    for (let pos = size; pos <= str_id.length - size; pos += size) {
+      const current_slice = str_id.slice(pos, pos + size);
+
+      if (current_slice !== baselise_slice) {
+        is_repeating = false;
+      }
+    }
+
+    if (is_repeating) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
+function is_id_mirror(id: number): boolean {
+  const str_id = id.toString();
+  if (str_id.length % 2 !== 0) {
+    return false;
+  }
+  const half_point = str_id.length / 2;
+  const left_side = str_id.slice(0, half_point);
+  const right_side = str_id.slice(half_point, str_id.length);
+  return left_side === right_side;
+}
+
+export async function read_id_ranges(path: string): Promise<Range[]> {
+  const raw_ranges = await Deno.readTextFile(path);
+  const raw_range_array = raw_ranges.split(",");
+  const id_range_list: Range[] = raw_range_array.map((range) => {
+    const value_array = range.split("-");
+    return {
+      init: parseInt(value_array[0]),
+      end: parseInt(value_array[1]),
+    };
+  });
+  return id_range_list;
+}