feat: day 4

aoc2024/inputs/1/day1.php

@@ -0,0 +1,31 @@
+<?php
+
+if(!file_exists("./input.txt")) {
+  echo "Missing input.txt\n";
+  exit(1);
+}
+
+$input = file_get_contents("./input.txt");
+
+$left = [];
+$right = [];
+$split_on = "   ";
+$lines = explode("\n", $input);
+
+foreach($lines as $line) {
+  $split = explode($split_on, $line);
+  $left[] = $split[0];
+  $right[] = $split[1];
+}
+
+sort($left);
+sort($right);
+
+$distances = [];
+for($i = 0; $i < count($left); $i++) {
+  $distances[] = abs($left[$i] - $right[$i]);
+}
+
+var_dump(array_sum($distances));
+
+?>

aoc2024/inputs/1/test-input.txt

@@ -3,4 +3,4 @@
 2   5
 1   3
 3   9
-3   3
+3   3

aoc2024/inputs/4/test-input.txt

@@ -0,0 +1,10 @@
+MMMSXXMASM
+MSAMXMSMSA
+AMXSXMAAMM
+MSAMASMSMX
+XMASAMXAMM
+XXAMMXXAMA
+SMSMSASXSS
+SAXAMASAAA
+MAMMMXMMMM
+MXMXAXMASX

aoc2024/src/days/day01.rs

@@ -62,16 +62,27 @@ impl Solution for Problem {
 #[cfg(test)]
 mod tests {
     const TEST_INPUT: &str = include_str!("../../inputs/1/test-input.txt");
+    const INPUT: &str = include_str!("../../inputs/1/input.txt");
 
     use super::*;
 
     #[test]
-    fn part1() {
+    fn part1_test() {
         assert_eq!(Problem.part_one(TEST_INPUT), "11");
     }
 
     #[test]
-    fn part2() {
+    fn part2_test() {
         assert_eq!(Problem.part_two(TEST_INPUT), "31");
     }
+
+    #[test]
+    fn part1() {
+        assert_eq!(Problem.part_one(INPUT), "2066446");
+    }
+
+    #[test]
+    fn part2() {
+        assert_eq!(Problem.part_two(INPUT), "24931009");
+    }
 }

aoc2024/src/days/day02.rs

@@ -64,16 +64,27 @@ impl Solution for Problem {
 #[cfg(test)]
 mod tests {
     const TEST_INPUT: &str = include_str!("../../inputs/2/test-input.txt");
+    const INPUT: &str = include_str!("../../inputs/2/input.txt");
 
     use super::*;
 
     #[test]
-    fn part1() {
+    fn part1_test() {
         assert_eq!(Problem.part_one(TEST_INPUT), "2");
     }
 
     #[test]
-    fn part2() {
+    fn part2_test() {
         assert_eq!(Problem.part_two(TEST_INPUT), "5");
     }
+
+    #[test]
+    fn part1() {
+        assert_eq!(Problem.part_one(INPUT), "326");
+    }
+
+    #[test]
+    fn part2() {
+        assert_eq!(Problem.part_two(INPUT), "381");
+    }
 }

aoc2024/src/days/day03.rs

@@ -85,16 +85,27 @@ impl Solution for Problem {
 mod tests {
     const TEST_INPUT: &str = include_str!("../../inputs/3/test-input.txt");
     const TEST_INPUT_2: &str = include_str!("../../inputs/3/test-input-2.txt");
+    const INPUT: &str = include_str!("../../inputs/3/input.txt");
 
     use super::*;
 
     #[test]
-    fn part1() {
+    fn part1_test() {
         assert_eq!(Problem.part_one(TEST_INPUT), "161");
     }
 
     #[test]
-    fn part2() {
+    fn part2_test() {
         assert_eq!(Problem.part_two(TEST_INPUT_2), "48");
     }
+
+    #[test]
+    fn part1() {
+        assert_eq!(Problem.part_one(INPUT), "178886550");
+    }
+
+    #[test]
+    fn part2() {
+        assert_eq!(Problem.part_two(INPUT), "87163705");
+    }
 }

aoc2024/src/days/day04.rs

@@ -0,0 +1,136 @@
+use crate::Solution;
+
+const SUB: &str = "XMAS";
+
+pub struct Problem;
+impl Solution for Problem {
+    fn part_one(&self, input: &str) -> String {
+        let mtx: Vec<Vec<char>> = input.lines().map(|line| line.chars().collect()).collect();
+        let mut permutations: Vec<String> = vec![];
+
+        let num_cols = mtx[0].len();
+        let num_rows = mtx.len();
+        // Rows
+        for row in input.lines() {
+            permutations.push(row.to_owned());
+        }
+
+        // Cols
+        for col in 0..num_cols {
+            let mut column = String::with_capacity(num_rows);
+            for row in 0..num_rows {
+                column.push(mtx[row][col]);
+            }
+            permutations.push(column.clone());
+        }
+
+        // Primary diagonals
+        for start in 0..(num_rows + num_cols - 1) {
+            let mut diag = String::new();
+            for row in 0..num_rows {
+                let col = start as isize - row as isize;
+                if col >= 0 && col < num_cols as isize {
+                    diag.push(mtx[row][col as usize]);
+                }
+            }
+            permutations.push(diag.clone());
+        }
+
+        // Secondary diagonals
+        for start in 0..(num_rows + num_cols - 1) {
+            let mut diag = String::new();
+            for row in 0..num_rows {
+                let col = start as isize - row as isize;
+                if col >= 0 && col < num_cols as isize {
+                    diag.push(mtx[row][num_cols - 1 - col as usize]);
+                }
+            }
+            permutations.push(diag.clone());
+        }
+
+        let mut count = 0;
+        for line in permutations {
+            count += line
+                .as_bytes()
+                .windows(SUB.len())
+                .filter(|&w| w == SUB.as_bytes())
+                .count();
+
+            let row_rev = line.chars().rev().collect::<String>();
+            count += row_rev
+                .as_bytes()
+                .windows(SUB.len())
+                .filter(|&w| w == SUB.as_bytes())
+                .count();
+        }
+
+        count.to_string()
+    }
+
+fn part_two(&self, input: &str) -> String {
+    // thank god part 2 is WAY easier.
+    let mtx: Vec<Vec<char>> = input.lines().map(|line| line.chars().collect()).collect();
+
+    let num_cols = mtx[0].len();
+    let num_rows = mtx.len();
+    let mut a_coords = vec![];
+
+    for row in 1..(num_rows - 1) {
+        for col in 1..(num_cols - 1) {
+            if mtx[row][col] == 'A' {
+                a_coords.push((row, col))
+            }
+        }
+    }
+    // check original coords
+    let mut count = 0;
+    for a in a_coords {
+        // check [-1, -1] up left
+        // check [1, 1] down right
+        let ul = mtx[a.0 - 1][a.1 - 1];
+        let dr = mtx[a.0 + 1][a.1 + 1];
+
+        // check [-1, 1] up right
+        // check [1, -1] down left
+        let ur = mtx[a.0 - 1][a.1 + 1];
+        let dl = mtx[a.0 + 1][a.1 - 1];
+
+        let urdl = format!("{}{}", ur, dl);
+        let uldr = format!("{}{}", ul, dr);
+
+        if (urdl == "SM" || urdl == "MS") && (uldr == "SM" || uldr == "MS") {
+            count += 1;
+        }
+    }
+
+    count.to_string()
+}
+}
+
+#[cfg(test)]
+mod tests {
+    const TEST_INPUT: &str = include_str!("../../inputs/4/test-input.txt");
+    const INPUT: &str = include_str!("../../inputs/4/input.txt");
+
+    use super::*;
+
+    #[test]
+    fn part1_test() {
+        assert_eq!(Problem.part_one(TEST_INPUT), "18");
+    }
+
+    #[test]
+    fn part2_test() {
+        assert_eq!(Problem.part_two(TEST_INPUT), "9");
+    }
+
+    #[test]
+    fn part1() {
+        assert_eq!(Problem.part_one(INPUT), "2547");
+    }
+
+    #[test]
+    fn part2() {
+        assert_eq!(Problem.part_two(INPUT), "1939");
+    }
+}

aoc2024/src/days/mod.rs

@@ -1,3 +1,4 @@
 pub mod day01;
 pub mod day02;
-pub mod day03;
+pub mod day03;
+pub mod day04;

aoc2024/src/dayselect.rs

@@ -5,6 +5,7 @@ pub fn select_day(day: usize) -> Option<Box<dyn Solution>> {
         1 => Some(Box::new(aoc2024::days::day01::Problem)),
         2 => Some(Box::new(aoc2024::days::day02::Problem)),
         3 => Some(Box::new(aoc2024::days::day03::Problem)),
+        4 => Some(Box::new(aoc2024::days::day04::Problem)),
         _ => None,
     }
 }