[2018][rust][3.0]

2018/rust/Cargo.lock

@@ -1,4 +1,95 @@
 [[package]]
 name = "advent_of_code_2018"
 version = "0.1.0"
+dependencies = [
+ "regex 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
+[[package]]
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+dependencies = [
+ "memchr 2.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "cfg-if"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "lazy_static"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "libc"
+version = "0.2.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "memchr"
+version = "2.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.44 (registry+https://github.com/rust-lang/crates.io-index)",
+ "version_check 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "regex"
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+]
+
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+dependencies = [
+ "ucd-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+name = "thread_local"
+version = "0.3.6"
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+dependencies = [
+ "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
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+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "utf8-ranges"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+name = "version_check"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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2018/rust/Cargo.toml

@@ -5,3 +5,4 @@ authors = ["Alpha Chen <alpha.chen@gmail.com>"]
 edition = "2018"
 
 [dependencies]
+regex = "1"

2018/rust/src/bin/day_03.rs

@@ -0,0 +1,120 @@
+use std::collections::HashMap;
+use std::error::Error;
+use std::io::{self, Read};
+use std::str::FromStr;
+
+use regex::Regex;
+
+fn main() -> Result<(), Box<Error>> {
+    let mut input = String::new();
+    io::stdin().read_to_string(&mut input)?;
+
+    let output = solve(&input)?;
+    println!("{}", output);
+
+    Ok(())
+}
+
+fn solve(input: &str) -> Result<String, Box<Error>> {
+    let claims: Vec<_> = input
+        .lines()
+        .map(str::trim)
+        .map(Claim::from_str)
+        .collect::<Result<_, _>>()?;
+    let fabric = claims.iter().fold(HashMap::new(), |mut fabric, claim| {
+        for square_inch in claim.square_inches() {
+            fabric
+                .entry(square_inch)
+                .and_modify(|count| *count += 1)
+                .or_insert(1);
+        }
+        fabric
+    });
+    let output = fabric.values().filter(|&&count| count > 1).count();
+    Ok(output.to_string())
+}
+
+#[test]
+fn test_solve() {
+    let input = r"
+        #1 @ 1,3: 4x4
+        #2 @ 3,1: 4x4
+        #3 @ 5,5: 2x2
+    "
+    .trim();
+
+    assert_eq!(&solve(input).unwrap(), "4");
+}
+
+#[derive(Debug, PartialEq, Eq)]
+struct Claim {
+    id: usize,
+    x: usize,
+    y: usize,
+    width: usize,
+    height: usize,
+}
+
+impl Claim {
+    fn square_inches(&self) -> impl Iterator<Item = (usize, usize)> + '_ {
+        (self.x..self.x + self.width)
+            .flat_map(move |x| (self.y..self.y + self.height).map(move |y| (x, y)))
+    }
+}
+
+#[test]
+fn test_claim_square_inches() {
+    let claim = Claim {
+        id: 1,
+        x: 2,
+        y: 3,
+        width: 4,
+        height: 4,
+    };
+    let square_inches: Vec<_> = claim.square_inches().collect();
+    assert_eq!(square_inches.len(), 16);
+    assert!(square_inches.contains(&(2, 3)));
+    assert!(square_inches.contains(&(5, 3)));
+    assert!(square_inches.contains(&(5, 6)));
+    assert!(square_inches.contains(&(2, 6)));
+}
+
+impl FromStr for Claim {
+    type Err = Box<Error>;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let re =
+            Regex::new(r"^#(?P<id>\d+) @ (?P<x>\d+),(?P<y>\d+): (?P<width>\d+)x(?P<height>\d+)$")
+                .unwrap();
+
+        let captures = re.captures(s).unwrap();
+        let id = captures.name("id").unwrap().as_str().parse()?;
+        let x = captures.name("x").unwrap().as_str().parse()?;
+        let y = captures.name("y").unwrap().as_str().parse()?;
+        let width = captures.name("width").unwrap().as_str().parse()?;
+        let height = captures.name("height").unwrap().as_str().parse()?;
+
+        Ok(Claim {
+            id,
+            x,
+            y,
+            width,
+            height,
+        })
+    }
+}
+
+#[test]
+fn test_claim_from_str() {
+    let claim = Claim::from_str("#1 @ 1,3: 4x4").unwrap();
+    assert_eq!(
+        claim,
+        Claim {
+            id: 1,
+            x: 1,
+            y: 3,
+            width: 4,
+            height: 4
+        }
+    );
+}