Move Day 4 to its own crate

2022/day4/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day4"
+version = "0.1.0"

2022/day4/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day4"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

2022/day4/src/main.rs

@@ -0,0 +1,96 @@
+use std::env;
+use std::fs;
+use std::ops::RangeInclusive;
+
+#[derive(PartialEq, PartialOrd)]
+struct RangeString(String);
+
+impl From<&str> for RangeString {
+    fn from(s: &str) -> Self {
+        RangeString(s.to_string())
+    }
+}
+
+impl From<RangeString> for RangeInclusive<u32> {
+    fn from(s: RangeString) -> Self {
+        let mut bounds = s.0.split("-");
+        let start = u32::from_str_radix(bounds.next().unwrap(), 10).unwrap();
+        let end = u32::from_str_radix(bounds.next().unwrap(), 10).unwrap();
+        assert!(bounds.next() == None);
+        start..=end
+    }
+}
+
+struct Assignment {
+    left: RangeInclusive<u32>,
+    right: RangeInclusive<u32>,
+}
+
+impl Assignment {
+    fn from_left_and_right_specifier(
+        left_specifier: RangeString,
+        right_specifier: RangeString,
+    ) -> Assignment {
+        Assignment {
+            left: RangeInclusive::<u32>::from(left_specifier),
+            right: RangeInclusive::<u32>::from(right_specifier),
+        }
+    }
+
+    fn has_range_contained_by_other(&self) -> bool {
+        let left_contains_right =
+            self.left.contains(self.right.start()) && self.left.contains(self.right.end());
+        let right_contains_left =
+            self.right.contains(self.left.start()) && self.right.contains(self.left.end());
+
+        left_contains_right || right_contains_left
+    }
+
+    fn has_overlapping_range(&self) -> bool {
+        self.left.contains(self.right.start())
+            || self.left.contains(self.right.end())
+            || self.right.contains(self.left.start())
+            || self.right.contains(self.left.end())
+    }
+}
+
+pub fn main() {
+    let args: Vec<String> = env::args().collect();
+
+    let filename = args.get(1).expect("Missing filename argument");
+
+    let file_contents = fs::read_to_string(&filename).expect("Unable to read file");
+
+    let assignment_counts: (u32, u32, u32) = file_contents.lines()
+        .map(|line| -> Assignment {
+            let mut elves = line.split(",").map(|s| RangeString::from(s));
+            let assignment = Assignment::from_left_and_right_specifier(
+                elves.next().unwrap(),
+                elves.next().unwrap(),
+            );
+
+            assert!(elves.next() == None);
+
+            assignment
+        })
+        .fold((0, 0, 0), |acc, a| {
+            let part1_counter = acc.1
+                + if a.has_range_contained_by_other() {
+                    1
+                } else {
+                    0
+                };
+            let part2_counter = acc.2 + if a.has_overlapping_range() { 1 } else { 0 };
+            (acc.0 + 1, part1_counter, part2_counter)
+        });
+
+    println!("Processed {} assignments", assignment_counts.0);
+    println!(
+        "Part 1: number of assignments with one range containing the other: {}",
+        assignment_counts.1
+    );
+    println!(
+        "Part 2: number of assignments with ranges at least partially overlapping: {}",
+        assignment_counts.2
+    );
+}