day4 complete

src/day4.rs

@@ -0,0 +1,84 @@
+use std::collections::HashSet;
+use std::fs;
+
+pub fn run() {
+    println!("Day 4:");
+    let input = fs::read_to_string("./inputs/day4.txt").expect("Could not read file");
+
+    println!("\tPart 1: {}", part1(&input));
+    println!("\tPart 2: {}", part2(&input));
+}
+
+struct SectionAssignment {
+    left: HashSet<usize>,
+    right: HashSet<usize>,
+}
+
+fn deserialize(line: &str) -> SectionAssignment {
+    let (left, right) = line.split_once(',').unwrap();
+    let left = left
+        .split_once('-')
+        .map(|(l, r)| l.parse().unwrap()..=r.parse().unwrap())
+        .unwrap()
+        .collect();
+    let right = right
+        .split_once('-')
+        .map(|(l, r)| l.parse().unwrap()..=r.parse().unwrap())
+        .unwrap()
+        .collect();
+
+    SectionAssignment { left, right }
+}
+
+fn part1(input: &str) -> usize {
+    let assignments = input.split_whitespace().map(deserialize);
+    let mut sum = 0;
+    for assignment in assignments {
+        if assignment.left.is_subset(&assignment.right)
+            || assignment.right.is_subset(&assignment.left)
+        {
+            sum += 1;
+        }
+    }
+    sum
+}
+
+fn part2(input: &str) -> usize {
+    let assignments = input.split_whitespace().map(deserialize);
+    let mut sum = 0;
+    for assignment in assignments {
+        if assignment.left.intersection(&assignment.right).count() >= 1 {
+            sum += 1;
+        }
+    }
+    sum
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_1() {
+        let input = "2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8";
+
+        assert_eq!(part1(input), 2);
+    }
+
+    #[test]
+    fn test_2() {
+        let input = "2-4,6-8
+    2-3,4-5
+    5-7,7-9
+    2-8,3-7
+    6-6,4-6
+    2-6,4-8";
+
+        assert_eq!(part2(input), 4);
+    }
+}

src/main.rs

@@ -1,9 +1,11 @@
 mod day1;
 mod day2;
 mod day3;
+mod day4;
 fn main() {
     println!("Running Advent of Code 2022");
     day1::run();
     day2::run();
     day3::run();
+    day4::run();
 }