From 0ed63a276efe3c06b5e15aaf6ecd94173a3d3f6a Mon Sep 17 00:00:00 2001
From: Pascal Syma <p.syma@appfarms.com>
Date: Mon, 1 Dec 2025 11:07:34 +0100
Subject: [PATCH] Solve 2025-01

---
 2025/01/2025-01.run.xml |  7 +++++++
 2025/01/index.test.ts   | 22 ++++++++++++++++++++
 2025/01/index.ts        | 45 +++++++++++++++++++++++++++++++++++++++++
 2025/01/run.ts          | 12 +++++++++++
 4 files changed, 86 insertions(+)
 create mode 100644 2025/01/2025-01.run.xml
 create mode 100644 2025/01/index.test.ts
 create mode 100644 2025/01/index.ts
 create mode 100644 2025/01/run.ts

diff --git a/2025/01/2025-01.run.xml b/2025/01/2025-01.run.xml
new file mode 100644
index 0000000..2c383da
--- /dev/null
+++ b/2025/01/2025-01.run.xml
@@ -0,0 +1,7 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="2025-01" type="BunRunConfiguration">
+    <option name="program" value="2025/01/run.ts" />
+    <option name="workingDirectory" value="$PROJECT_DIR$" />
+    <method v="2" />
+  </configuration>
+</component>
\ No newline at end of file
diff --git a/2025/01/index.test.ts b/2025/01/index.test.ts
new file mode 100644
index 0000000..6999a82
--- /dev/null
+++ b/2025/01/index.test.ts
@@ -0,0 +1,22 @@
+import { describe, expect, it } from 'bun:test';
+import { solveFirst, solveSecond } from './index.ts';
+
+describe('2025-01', () => {
+  const testInput = `L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82`;
+  it('first', () => {
+    expect(solveFirst(testInput)).toBe(3);
+  });
+  it('second', () => {
+    expect(solveSecond(testInput)).toBe(6);
+    expect(solveSecond(`R1000`)).toBe(10);
+  });
+});
diff --git a/2025/01/index.ts b/2025/01/index.ts
new file mode 100644
index 0000000..67e7996
--- /dev/null
+++ b/2025/01/index.ts
@@ -0,0 +1,45 @@
+import { mod } from '../../utils/numbers.ts';
+
+const size = 100;
+const initialValue = 50;
+
+function parseInput(input: string) {
+  const regex = /^([LR])(\d*)$/gm;
+  const match = input.matchAll(regex);
+
+  return Array.from(match, (m) => Number(m[2]) * (m[1] === 'L' ? -1 : 1));
+}
+
+export function solveFirst(input: string): number {
+  let zeros = 0;
+  parseInput(input).reduce((d, r) => {
+    const newDial = (d + r) % size;
+    if (newDial === 0) {
+      zeros++;
+    }
+    return newDial;
+  }, initialValue);
+
+  return zeros;
+}
+export function solveSecond(input: string): number {
+  const rots = parseInput(input);
+
+  let zeros = 0;
+  let dial = initialValue;
+
+  // brute force is easier than thinking
+  for (const rot of rots) {
+    if (rot === 0) {
+      continue;
+    }
+    for (let i = 0; i < Math.abs(rot); i++) {
+      dial = mod(dial + (rot > 0 ? 1 : -1), size);
+      if (dial === 0) {
+        zeros++;
+      }
+    }
+  }
+
+  return zeros;
+}
diff --git a/2025/01/run.ts b/2025/01/run.ts
new file mode 100644
index 0000000..88783cd
--- /dev/null
+++ b/2025/01/run.ts
@@ -0,0 +1,12 @@
+import { join } from 'path';
+import { solveFirst, solveSecond } from './index.ts';
+
+const input = await Bun.file(join(__dirname, 'input.txt')).text();
+
+const firstAnswer = solveFirst(input);
+
+console.log(firstAnswer);
+
+const secondAnswer = solveSecond(input);
+
+console.log(secondAnswer);