[2025] Solution for Day 5

Author: kfarnung

2025/src/bin/day05.rs

@@ -0,0 +1,16 @@
+use aoc2025::days::day05::{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

@@ -2,3 +2,4 @@ pub mod day01;
 pub mod day02;
 pub mod day03;
 pub mod day04;
+pub mod day05;

2025/src/days/day05.rs

@@ -0,0 +1,84 @@
+pub fn part1(contents: &str) -> i64 {
+    let (ranges, available) = parse_input(contents);
+    let mut count = 0;
+    for b in available {
+        for r in &ranges {
+            if b >= r.0 && b <= r.1 {
+                count += 1;
+                break;
+            }
+        }
+    }
+    count
+}
+
+pub fn part2(contents: &str) -> i64 {
+    let (mut ranges, _) = parse_input(contents);
+    ranges.sort_by(|a, b| a.0.cmp(&b.0));
+    let mut merged_ranges = Vec::new();
+    let mut current_merged = ranges[0];
+    for r in ranges.iter().skip(1) {
+        if r.0 <= current_merged.1 {
+            current_merged.1 = current_merged.1.max(r.1);
+        } else {
+            merged_ranges.push(current_merged);
+            current_merged = r.clone();
+        }
+    }
+    merged_ranges.push(current_merged);
+
+    let mut count = 0;
+    for r in merged_ranges {
+        count += r.1 - r.0 + 1;
+    }
+    count
+}
+
+fn parse_input(contents: &str) -> (Vec<(i64, i64)>, Vec<i64>) {
+    let lines = contents.lines();
+    let mut ranges = Vec::new();
+    let mut available = Vec::new();
+    let mut found_blank = false;
+
+    for l in lines {
+        if l.is_empty() {
+            found_blank = true;
+            continue;
+        }
+
+        if !found_blank {
+            let parts: Vec<&str> = l.split('-').collect();
+            let start = parts[0].parse::<i64>().unwrap();
+            let end = parts[1].parse::<i64>().unwrap();
+            ranges.push((start, end));
+        } else {
+            let blocked_value = l.parse::<i64>().unwrap();
+            available.push(blocked_value);
+        }
+    }
+
+    (ranges, available)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part1() {
+        let input = vec![
+            "3-5", "10-14", "16-20", "12-18", "", "1", "5", "8", "11", "17", "32",
+        ];
+
+        assert_eq!(part1(&input.join("\n")), 3);
+    }
+
+    #[test]
+    fn test_part2() {
+        let input = vec![
+            "3-5", "10-14", "16-20", "12-18", "", "1", "5", "8", "11", "17", "32",
+        ];
+
+        assert_eq!(part2(&input.join("\n")), 14);
+    }
+}

2025/tests/day05.rs

@@ -0,0 +1,13 @@
+use aoc2025::days::day05::{part1, part2};
+
+#[test]
+fn test_part1() {
+    let content = std::include_str!("../../private/inputs/2025/day05.txt");
+    assert_eq!(part1(&content), 679);
+}
+
+#[test]
+fn test_part2() {
+    let content = std::include_str!("../../private/inputs/2025/day05.txt");
+    assert_eq!(part2(&content), 358155203664116);
+}