1st day

Author: majcn

data/examples/01.txt

@@ -0,0 +1,6 @@
+3   4
+4   3
+2   5
+1   3
+3   9
+3   3

src/bin/01.rs

@@ -0,0 +1,68 @@
+advent_of_code::solution!(1);
+
+use advent_of_code::maneatingape::parse::*;
+use advent_of_code::maneatingape::hash::*;
+
+fn parse_data(input: &str) -> (Vec<u32>, Vec<u32>) {
+    let first = input
+        .lines()
+        .map(|line| line.iter_unsigned().next().unwrap())
+        .collect();
+    let second = input
+        .lines()
+        .map(|line| line.iter_unsigned().nth(1).unwrap())
+        .collect();
+
+    (first, second)
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let (mut left, mut right) = parse_data(input);
+
+    left.sort_unstable();
+    right.sort_unstable();
+
+    let result = left
+        .into_iter()
+        .zip(right)
+        .map(|(x, y)| u32::abs_diff(x, y))
+        .sum();
+
+    Some(result)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let (left, right) = parse_data(input);
+
+    let mut right_counter = FastMap::new();
+    for item in right {
+        *right_counter.entry(item).or_default() += 1;
+    }
+
+    let result = left
+        .into_iter()
+        .map(|x| match right_counter.get(&x) {
+            Some(v) => x * v,
+            None => 0,
+        })
+        .sum();
+
+    Some(result)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(11));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(31));
+    }
+}