2025 Day 01

.github/workflows/code-quality.yml

@@ -12,9 +12,9 @@ jobs:
 
     strategy:
       matrix:
-        php: [ 8.3, 8.4 ]
+        php: [ 8.3, 8.4, 8.5 ]
         os: [ ubuntu-latest ]
-        year: [ 2015, 2018, 2019, 2020, 2021, 2022, 2023, 2024 ]
+        year: [ 2015, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 ]
 
     name: Unit Tests for Year ${{ matrix.year }} (PHP ${{ matrix.php }})
 

2025/day-01.php

@@ -0,0 +1,131 @@
+<?php
+
+require __DIR__ . '/../vendor/autoload.php';
+
+use adventofcode\Year2025\SafeCracker;
+
+/**
+ * --- Day 1: Secret Entrance ---
+ *
+ * The Elves have good news and bad news.
+ *
+ * The good news is that they've discovered project management! This has given them the tools they need to prevent their
+ * usual Christmas emergency. For example, they now know that the North Pole decorations need to be finished soon so
+ * that other critical tasks can start on time.
+ *
+ * The bad news is that they've realized they have a different emergency: according to their resource planning, none of
+ * them have any time left to decorate the North Pole!
+ *
+ * To save Christmas, the Elves need you to finish decorating the North Pole by December 12th.
+ *
+ * Collect stars by solving puzzles. Two puzzles will be made available on each day; the second puzzle is unlocked when
+ * you complete the first. Each puzzle grants one star. Good luck!
+ *
+ * You arrive at the secret entrance to the North Pole base ready to start decorating. Unfortunately, the password seems
+ * to have been changed, so you can't get in. A document taped to the wall helpfully explains:
+ *
+ * "Due to new security protocols, the password is locked in the safe below. Please see the attached document for the
+ * new combination."
+ *
+ * The safe has a dial with only an arrow on it; around the dial are the numbers 0 through 99 in order. As you turn the
+ * dial, it makes a small click noise as it reaches each number.
+ *
+ * The attached document (your puzzle input) contains a sequence of rotations, one per line, which tell you how to open
+ * the safe. A rotation starts with an L or R which indicates whether the rotation should be to the left (toward lower
+ * numbers) or to the right (toward higher numbers). Then, the rotation has a distance value which indicates how many
+ * clicks the dial should be rotated in that direction.
+ *
+ * So, if the dial were pointing at 11, a rotation of R8 would cause the dial to point at 19. After that, a rotation of
+ * L19 would cause it to point at 0.
+ *
+ * Because the dial is a circle, turning the dial left from 0 one click makes it point at 99. Similarly, turning the
+ * dial right from 99 one click makes it point at 0.
+ *
+ * So, if the dial were pointing at 5, a rotation of L10 would cause it to point at 95. After that, a rotation of R5
+ * could cause it to point at 0.
+ *
+ * The dial starts by pointing at 50.
+ *
+ * You could follow the instructions, but your recent required official North Pole secret entrance security training
+ * seminar taught you that the safe is actually a decoy. The actual password is the number of times the dial is left
+ * pointing at 0 after any rotation in the sequence.
+ *
+ * For example, suppose the attached document contained the following rotations:
+ *
+ * L68
+ * L30
+ * R48
+ * L5
+ * R60
+ * L55
+ * L1
+ * L99
+ * R14
+ * L82
+ *
+ * Following these rotations would cause the dial to move as follows:
+ *
+ *  - The dial starts by pointing at 50.
+ *  - The dial is rotated L68 to point at 82.
+ *  - The dial is rotated L30 to point at 52.
+ *  - The dial is rotated R48 to point at 0.
+ *  - The dial is rotated L5 to point at 95.
+ *  - The dial is rotated R60 to point at 55.
+ *  - The dial is rotated L55 to point at 0.
+ *  - The dial is rotated L1 to point at 99.
+ *  - The dial is rotated L99 to point at 0.
+ *  - The dial is rotated R14 to point at 14.
+ *  - The dial is rotated L82 to point at 32.
+ *
+ * Because the dial points at 0 a total of three times during this process, the password in this example is 3.
+ *
+ * Analyze the rotations in your attached document. What's the actual password to open the door?
+ */
+
+$safeCracker = new SafeCracker();
+
+$instructions = file(__DIR__ . '/inputs/day-01.input', FILE_IGNORE_NEW_LINES);
+
+$totalZeros = $safeCracker->findPointedAtZerosFromInstructions($instructions);
+print('The total times zero was pointed at was ' . $totalZeros . ".\n");
+
+/**
+ * --- Part Two ---
+ *
+ * You're sure that's the right password, but the door won't open. You knock, but nobody answers. You build a snowman
+ * while you think.
+ *
+ * As you're rolling the snowballs for your snowman, you find another security document that must have fallen into
+ * the snow:
+ *
+ * "Due to newer security protocols, please use password method 0x434C49434B until further notice."
+ *
+ * You remember from the training seminar that "method 0x434C49434B" means you're actually supposed to count the number
+ * of times any click causes the dial to point at 0, regardless of whether it happens during a rotation or at the end
+ * of one.
+ *
+ * Following the same rotations as in the above example, the dial points at zero a few extra times during its rotations:
+ *
+ * The dial starts by pointing at 50.
+ * The dial is rotated L68 to point at 82; during this rotation, it points at 0 once.
+ * The dial is rotated L30 to point at 52.
+ * The dial is rotated R48 to point at 0.
+ * The dial is rotated L5 to point at 95.
+ * The dial is rotated R60 to point at 55; during this rotation, it points at 0 once.
+ * The dial is rotated L55 to point at 0.
+ * The dial is rotated L1 to point at 99.
+ * The dial is rotated L99 to point at 0.
+ * The dial is rotated R14 to point at 14.
+ * The dial is rotated L82 to point at 32; during this rotation, it points at 0 once.
+ *
+ * In this example, the dial points at 0 three times at the end of a rotation, plus three more times during a rotation.
+ * So, in this example, the new password would be 6.
+ *
+ * Be careful: if the dial were pointing at 50, a single rotation like R1000 would cause the dial to point at 0 ten
+ * times before returning back to 50!
+ *
+ * Using password method 0x434C49434B, what is the password to open the door?
+ */
+
+$totalZeros = $safeCracker->findZerosHitFromInstructions($instructions);
+print('The total times zero was hit was ' . $totalZeros . ".\n");

2025/inputs/day-01-sample.input

@@ -0,0 +1,10 @@
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82