y2025d2

y2025/src/bin/d2.rs

@@ -0,0 +1,27 @@
+use std::{fs, time::Instant};
+
+use utils::time::get_elapsed_string;
+use y2025::days::d2;
+
+fn main() {
+    let now = Instant::now();
+    println!("Part 1:");
+    part1();
+    println!("Ran in {}", get_elapsed_string(now.elapsed()));
+    let now = Instant::now();
+    println!("Part 2:");
+    part2();
+    println!("Ran in {}", get_elapsed_string(now.elapsed()));
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/2_input.txt")).unwrap();
+    println!("{}", d2::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/2_input.txt")).unwrap();
+    println!("{}", d2::process_part2(&content));
+}

y2025/src/days/d2.rs

@@ -0,0 +1,91 @@
+use itertools::Itertools;
+
+pub fn process_part1(input: &str) -> i64 {
+    input
+        .split(',')
+        .map(|range| range.split_once('-').unwrap())
+        .map(|(start, end)| {
+            (
+                start
+                    .parse::<i64>()
+                    .expect(&format!("Cannot parse start from {start}")),
+                end.trim_end()
+                    .parse::<i64>()
+                    .expect(&format!("Cannot parse end from {end}")),
+            )
+        })
+        .map(|(start, end)| {
+            (start..=end)
+                .map(|id| {
+                    let id_str = format!("{id}");
+                    if id_str.starts_with('0') {
+                        return 0;
+                    }
+                    let (left, right) = id_str.split_at(id_str.len() / 2);
+                    if left == right {
+                        return id;
+                    }
+                    0
+                })
+                .sum::<i64>()
+        })
+        .sum()
+}
+
+pub fn process_part2(input: &str) -> i64 {
+    input
+        .split(',')
+        .map(|range| range.split_once('-').unwrap())
+        .map(|(start, end)| {
+            (
+                start
+                    .parse::<i64>()
+                    .expect(&format!("Cannot parse start from {start}")),
+                end.trim_end()
+                    .parse::<i64>()
+                    .expect(&format!("Cannot parse end from {end}")),
+            )
+        })
+        .map(|(start, end)| {
+            (start..=end)
+                .map(|id| {
+                    let id_str = format!("{id}");
+                    if id_str.starts_with('0') {
+                        return 0;
+                    }
+                    for num_parts in 2..=id_str.len() {
+                        let parts = id_str
+                            .chars()
+                            .chunks(id_str.len() / num_parts)
+                            .into_iter()
+                            .map(|chunk| chunk.collect::<String>())
+                            .collect::<Vec<String>>();
+                        if parts.iter().all_equal() {
+                            return id;
+                        }
+                    }
+                    0
+                })
+                .sum::<i64>()
+        })
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const INPUT: &str = "11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124";
+
+    #[test]
+    fn part1() {
+        let result = process_part1(INPUT);
+        assert_eq!(result, 1227775554);
+    }
+
+    #[test]
+    fn part2() {
+        let result = process_part2(INPUT);
+        assert_eq!(result, 4174379265);
+    }
+}

y2025/src/days/mod.rs

@@ -1 +1,3 @@
 pub mod d1;
+
+pub mod d2;