day2: first impl

inputs/2.test

···
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124

inputs/2.txt

···
+18623-26004,226779-293422,65855-88510,868-1423,248115026-248337139,903911-926580,97-121,67636417-67796062,24-47,6968-10197,193-242,3769-5052,5140337-5233474,2894097247-2894150301,979582-1016336,502-646,9132195-9191022,266-378,58-91,736828-868857,622792-694076,6767592127-6767717303,2920-3656,8811329-8931031,107384-147042,941220-969217,3-17,360063-562672,7979763615-7979843972,1890-2660,23170346-23308802

src/main.rs

···
 mod solutions;
 
-use solutions::Day1;
+use solutions::Day2;
 
 fn main() {
-    let day1 = Day1::new("inputs/1.txt");
-    println!("Part 1: {}, Part 2: {}", day1.part1(), day1.part2());
+    //let day1 = Day1::new("inputs/1.txt");
+    let day = Day2::new("inputs/2.txt");
+    println!("Part 1: {}", day.part1());
+    println!("Part 2: {}", day.part2());
 }

src/solutions/day2.rs

···
+use std::fs;
+
+pub struct Day2 {
+    data: String,
+}
+
+fn divisors_desc(n: usize) -> impl Iterator<Item = usize> {
+    (1..n).rev().filter(move |&i| n % i == 0)
+}
+
+fn invalid_id(id: &i64) -> bool {
+    let str_id = id.to_string();
+    if str_id.len() % 2 != 0 {
+        return false;
+    }
+    let (left, right) = str_id.split_at(str_id.len() / 2);
+    left == right
+}
+
+fn new_invalid_id(id: &i64) -> bool {
+    let str_id = id.to_string();
+    for div in divisors_desc(str_id.len()) {
+        let chars = str_id.chars().collect::<Vec<char>>();
+        let seqs = chars.chunks(div).collect::<Vec<_>>();
+        if seqs.iter().all(|&seq| seq == seqs[0]) {
+            return true;
+        }
+    }
+    false
+}
+
+impl Day2 {
+    pub fn new(path: &str) -> Self {
+        Self {
+            data: fs::read_to_string(path).expect("failed to read input file"),
+        }
+    }
+
+    pub fn part1(&self) -> i64 {
+        self.data.split(',').fold(0, |acc, range| {
+            let (n1, n2) = range.split_once('-').unwrap();
+            println!("Range: {}-{}", n1, n2);
+            let (n1, n2) = (n1.parse::<i64>().unwrap(), n2.parse::<i64>().unwrap());
+            println!("Range: {}-{}", n1, n2);
+            (n1..=n2).filter(|x| invalid_id(x)).sum::<i64>() + acc
+        })
+    }
+
+    pub fn part2(&self) -> i64 {
+        self.data.split(',').fold(0, |acc, range| {
+            let (n1, n2) = range.split_once('-').unwrap();
+            println!("Range: {}-{}", n1, n2);
+            let (n1, n2) = (n1.parse::<i64>().unwrap(), n2.parse::<i64>().unwrap());
+            println!("Range: {}-{}", n1, n2);
+            (n1..=n2).filter(|x| new_invalid_id(x)).sum::<i64>() + acc
+        })
+    }
+}

src/solutions/mod.rs

···
 pub mod day1;
+pub mod day2;
 pub use day1::Day1;
+pub use day2::Day2;