[2025] Solution for Day 6

Author: kfarnung

2025/src/bin/day06.rs

@@ -0,0 +1,16 @@
+use aoc2025::days::day06::{part1, part2};
+use std::env;
+use std::fs;
+use std::process;
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    if args.len() < 2 {
+        println!("Missing required arguments");
+        process::exit(1);
+    }
+
+    let contents = fs::read_to_string(&args[1]).expect("Something went wrong");
+    println!("Part 1: {}", part1(&contents));
+    println!("Part 2: {}", part2(&contents));
+}

2025/src/days.rs

@@ -3,3 +3,4 @@ pub mod day02;
 pub mod day03;
 pub mod day04;
 pub mod day05;
+pub mod day06;

2025/src/days/day06.rs

@@ -0,0 +1,102 @@
+pub fn part1(contents: &str) -> i64 {
+    let split_lines: Vec<Vec<&str>> = contents
+        .lines()
+        .map(|line| line.split_whitespace().collect())
+        .collect();
+
+    let mut parsed_input = Vec::new();
+    for i in 0..split_lines[0].len() {
+        let mut column = Vec::new();
+        for j in 0..split_lines.len() - 1 {
+            let cell = &split_lines[j][i];
+            column.push(cell.parse::<i64>().unwrap());
+        }
+        parsed_input.push((
+            column,
+            split_lines[split_lines.len() - 1][i]
+                .chars()
+                .next()
+                .unwrap(),
+        ));
+    }
+
+    let mut result = 0;
+    for (column, operation) in parsed_input {
+        match operation {
+            '+' => result += column.iter().sum::<i64>(),
+            '*' => result += column.iter().product::<i64>(),
+            _ => panic!("Unknown operation"),
+        }
+    }
+
+    result
+}
+
+pub fn part2(contents: &str) -> i64 {
+    let lines: Vec<Vec<char>> = contents
+        .lines()
+        .map(|line| line.chars().collect())
+        .collect();
+
+    let mut result = 0;
+    let mut numbers = Vec::new();
+
+    for i in (0..lines[0].len()).rev() {
+        let mut found_number = false;
+        let mut number = 0;
+        let mut multiplier = 1;
+
+        for j in (0..lines.len() - 1).rev() {
+            if lines[j][i] == ' ' {
+                continue;
+            }
+            found_number = true;
+            number += (lines[j][i].to_digit(10).unwrap() as i64) * multiplier;
+            multiplier *= 10;
+        }
+
+        if found_number {
+            numbers.push(number);
+        }
+
+        if lines[lines.len() - 1][i] != ' ' {
+            match lines[lines.len() - 1][i] {
+                '+' => result += numbers.iter().sum::<i64>(),
+                '*' => result += numbers.iter().product::<i64>(),
+                _ => panic!("Unknown operation"),
+            }
+            numbers.clear();
+        }
+    }
+
+    result
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part1() {
+        let input = vec![
+            "123 328  51 64 ",
+            " 45 64  387 23 ",
+            "  6 98  215 314",
+            "*   +   *   +  ",
+        ];
+
+        assert_eq!(part1(&input.join("\n")), 4277556);
+    }
+
+    #[test]
+    fn test_part2() {
+        let input = vec![
+            "123 328  51 64 ",
+            " 45 64  387 23 ",
+            "  6 98  215 314",
+            "*   +   *   +  ",
+        ];
+
+        assert_eq!(part2(&input.join("\n")), 3263827);
+    }
+}

2025/tests/day06.rs

@@ -0,0 +1,13 @@
+use aoc2025::days::day06::{part1, part2};
+
+#[test]
+fn test_part1() {
+    let content = std::include_str!("../../private/inputs/2025/day06.txt");
+    assert_eq!(part1(&content), 6299564383938);
+}
+
+#[test]
+fn test_part2() {
+    let content = std::include_str!("../../private/inputs/2025/day06.txt");
+    assert_eq!(part2(&content), 11950004808442);
+}