Day 01

Cargo.toml

@@ -31,6 +31,10 @@ name = "template"
 path = "src/day00/main.rs"
 test = false
 
+[[bin]]
+name = "day01"
+path = "src/day01/main.rs"
+
 [dependencies]
 reqwest = { version = "0.12.9", features = ["blocking"] }
 

src/day01/main.rs

@@ -0,0 +1,92 @@
+pub const INPUT: &str = include_str!("./input.txt");
+
+fn parse_input(input: &'static str) -> Vec<[u32; 2]> {
+    let input = input
+        .lines()
+        .map(|line| -> [u32; 2] {
+            let nums = line
+                .split_whitespace()
+                .map(|num| num.parse::<u32>().unwrap())
+                .collect::<Vec<_>>();
+            [nums[0], nums[1]]
+        })
+        .collect::<Vec<_>>();
+    input
+}
+
+pub fn main() {
+    let input = parse_input(INPUT);
+    let result_1 = part_1(&input);
+    println!("{result_1}");
+    let result_2 = part_2(&input);
+    println!("{result_2}");
+}
+
+fn part_1(input: &Vec<[u32; 2]>) -> u32 {
+    let mut left = vec![];
+    let mut right = vec![];
+    for pair in input {
+        left.push(pair[0]);
+        right.push(pair[1]);
+    }
+    left.sort_unstable();
+    right.sort_unstable();
+    let mut diff = 0;
+    for i in 0..left.len() {
+        diff += u32::abs_diff(left[i], right[i]);
+    }
+    diff
+}
+
+fn part_2(input: &Vec<[u32; 2]>) -> u32 {
+    let mut left = vec![];
+    let mut right = vec![];
+    for pair in input {
+        left.push(pair[0]);
+        right.push(pair[1]);
+    }
+
+    let mut result = 0;
+
+    for num in left {
+        result += num * right.iter().filter(|&&x| x == num).count() as u32;
+    }
+
+    result
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::parse_input;
+
+    const SAMPLE_INPUT: &str = r#"3   4
+4   3
+2   5
+1   3
+3   9
+3   3"#;
+
+    #[test]
+    fn test_part_1_with_sample_solution() {
+        let input = parse_input(SAMPLE_INPUT);
+        assert_eq!(super::part_1(&input), 11)
+    }
+
+    #[test]
+    fn test_part_1_with_solution() {
+        let input = parse_input(super::INPUT);
+        assert_eq!(super::part_1(&input), 2192892);
+    }
+
+    #[test]
+    fn test_part_2_with_sample_solution() {
+        let input = parse_input(SAMPLE_INPUT);
+        assert_eq!(super::part_2(&input), 31)
+    }
+
+    #[test]
+    fn test_part_2_with_solution() {
+        let input = parse_input(super::INPUT);
+        assert_eq!(super::part_2(&input), 22962826);
+    }
+}