day 1

Author: prevostc

Cargo.lock

@@ -24,6 +24,7 @@ test_lib = []
 # Template dependencies
 chrono = { version = "0.4.38", optional = true }
 dhat = { version = "0.3.3", optional = true }
+itertools = "0.13.0"
 pico-args = "0.5.0"
 tinyjson = "2.5.1"
 

Cargo.toml

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

data/examples/01.txt

@@ -0,0 +1,57 @@
+advent_of_code::solution!(1);
+use itertools::Itertools;
+
+fn parse_input(input: &str) -> (Vec<u32>, Vec<u32>) {
+    let mut l1 = Vec::with_capacity(1000);
+    let mut l2 = Vec::with_capacity(1000);
+    for line in input.lines() {
+        let mut parts = line.split_whitespace();
+        let n1 = parts.next().unwrap().parse::<u32>().unwrap();
+        let n2 = parts.next().unwrap().parse::<u32>().unwrap();
+        l1.push(n1);
+        l2.push(n2);
+    }
+    (l1, l2)
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let (mut l1, mut l2) = parse_input(input);
+
+    l1.sort();
+    l2.sort();
+
+    let mut total = 0;
+    for (n1, n2) in l1.iter().zip(l2.iter()) {
+        total += n1.abs_diff(*n2);
+    }
+    Some(total)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let (l1, l2) = parse_input(input);
+    let freq = l2.iter().counts();
+    let mut total = 0;
+    for n1 in l1 {
+        if let Some(&n2) = freq.get(&n1) {
+            total += n1 * n2 as u32;
+        }
+    }
+    Some(total)
+}
+
+#[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));
+    }
+}