day 4

.gitignore

@@ -1,4 +1,3 @@
 target/
-input
+*input
-testinput
 main

day04/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "day04"
+version = "0.1.0"

day04/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day04"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day04/src/main.rs

@@ -0,0 +1,59 @@
+use std::io::{self, BufRead};
+use std::num::ParseIntError;
+use std::str::FromStr;
+
+#[derive(Debug)]
+struct Pair {
+    first: (usize, usize),
+    second: (usize, usize),
+}
+
+fn main() {
+    let pairs = io::stdin()
+        .lock()
+        .lines()
+        .map(|l| Pair::from_str(l.unwrap().as_str()).unwrap());
+
+    let mut full_overlap = 0;
+    let mut partial_overlap = 0;
+
+    for pair in pairs {
+        if (pair.first.0 >= pair.second.0 && pair.first.1 <= pair.second.1)
+            || (pair.first.0 <= pair.second.0 && pair.first.1 >= pair.second.1)
+        {
+            full_overlap += 1;
+        }
+
+        if (pair.first.0 >= pair.second.0 && pair.first.0 <= pair.second.1)
+            || (pair.first.1 >= pair.second.0 && pair.first.1 <= pair.second.1)
+            || (pair.second.0 >= pair.first.0 && pair.second.0 <= pair.first.1)
+            || (pair.second.1 >= pair.first.0 && pair.second.1 <= pair.first.1)
+        {
+            partial_overlap += 1;
+        }
+    }
+
+    println!("P1: {}, P2: {}", full_overlap, partial_overlap);
+}
+
+impl FromStr for Pair {
+    type Err = ParseIntError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let (first, second) = s.split_once(',').unwrap();
+        let first_half = first.split_once('-').unwrap();
+        let first_half = (
+            first_half.0.parse::<usize>().unwrap(),
+            first_half.1.parse::<usize>().unwrap(),
+        );
+        let second_half = second.split_once('-').unwrap();
+        let second_half = (
+            second_half.0.parse::<usize>().unwrap(),
+            second_half.1.parse::<usize>().unwrap(),
+        );
+        Ok(Pair {
+            first: first_half,
+            second: second_half,
+        })
+    }
+}