day 13 (part 1) (#13)

13/final_input.txt

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+1003055
+37,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,41,x,x,x,x,x,x,x,x,x,433,x,x,x,x,x,x,x,23,x,x,x,x,x,x,x,x,17,x,19,x,x,x,x,x,x,x,x,x,29,x,593,x,x,x,x,x,x,x,x,x,x,x,x,13

13/readme.md

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+#Day 13: Shuttle Search
+https://adventofcode.com/2020/day/13

13/src/13.ts

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+export function countPart1(input: string[]): number
+{
+    const now = Number(input[0]);
+    const workingBuses = input[1].split(",").filter(line => line !== 'x').map(Number);
+    let minTimeArrival: [number, number] = [Infinity, 0];
+
+    for (const bus of workingBuses) {
+        const arrival = Math.ceil(now / bus) * bus;
+        if (minTimeArrival[0] > arrival) {
+            minTimeArrival = [arrival, bus];
+        }
+    }
+
+    return (minTimeArrival[0] - now) * minTimeArrival[1];
+}
+
+// part 2 not implemented

13/tests/13.test.ts

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+import {assertStrictEquals} from "../../deps.ts";
+import {countPart1} from "../src/13.ts";
+
+Deno.test("ShuttleSearch: Example test from introduction (Part one)", () => {
+  const input = [
+      "939",
+      "7,13,x,x,59,x,31,19"
+  ];
+  const expectedOutput = 295;
+
+  assertStrictEquals(countPart1(input), expectedOutput);
+});
+
+Deno.test("ShuttleSearch: Final test (Part one)", () => {
+  const input = (
+      Deno.readTextFileSync("13/final_input.txt").trimEnd()
+  ).split("\n");
+
+  const expectedOutput = 410;
+
+  assertStrictEquals(countPart1(input), expectedOutput);
+});
+
+// part 2 not implemented