Refactor to struct and enumerate steps

src/day_three.rs

@@ -1,50 +1,60 @@
+use std::cmp::Ordering;
 use std::collections::BTreeSet;
 use std::io;
 use std::iter::{repeat, successors};
 
-fn next(c: (i32, i32), direction: &str) -> (i32, i32) {
+#[derive(Copy, Clone, Eq, Debug)]
+struct Coord(usize, (i32, i32));
+
+impl PartialEq for Coord {
+    fn eq(&self, other: &Self) -> bool {
+        self.1 == other.1
+    }
+}
+
+impl Ord for Coord {
+    fn cmp(&self, other: &Self) -> Ordering {
+        (self.1).cmp(&(other.1))
+    }
+}
+
+impl PartialOrd for Coord {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.1.partial_cmp(&other.1)
+    }
+}
+
+fn next(c: (i32, i32), direction: char) -> (i32, i32) {
     match direction {
-        "R" => (c.0 + 1, c.1),
-        "L" => (c.0 - 1, c.1),
-        "U" => (c.0, c.1 + 1),
-        "D" => (c.0, c.1 - 1),
+        'R' => (c.0 + 1, c.1),
+        'L' => (c.0 - 1, c.1),
+        'U' => (c.0, c.1 + 1),
+        'D' => (c.0, c.1 - 1),
         _ => panic!("Wrong direction format!"),
     }
 }
 
-fn direction_length(entry: String) -> (String, usize) {
-    (
-        entry.chars().nth(0).unwrap().to_string(),
-        entry[1..].parse().unwrap(),
-    )
-}
-
-fn to_coordinates(entries: Vec<String>) -> BTreeSet<(i32, i32)> {
+fn to_coordinates(entries: Vec<String>) -> BTreeSet<Coord> {
     let mut wire = BTreeSet::new();
 
     let mut it = entries
         .into_iter()
-        .map(direction_length)
+        .map(|entry| (entry.chars().nth(0).unwrap(), entry[1..].parse().unwrap()))
         .flat_map(|(direction, length)| repeat(direction).take(length));
 
-    successors(
-        it.next()
-            .map(|direction| (next((0, 0), direction.as_ref()))),
-        |c| it.next().map(|direction| (next(*c, direction.as_ref()))),
-    )
+    successors(it.next().map(|direction| (next((0, 0), direction))), |c| {
+        it.next().map(|direction| (next(*c, direction)))
+    })
+    .enumerate()
     .for_each(|c| {
-        wire.insert(c);
+        wire.insert(Coord(c.0 + 1, c.1));
     });
 
     wire
 }
 
-fn distance(position: (i32, i32)) -> i32 {
-    position.0.abs() + position.1.abs()
-}
-
-fn closest(input: String) -> Option<i32> {
-    let entries: Vec<BTreeSet<(i32, i32)>> = input
+fn closest(input: &str) -> Option<i32> {
+    let entries: Vec<BTreeSet<Coord>> = input
         .trim()
         .split("\n")
         .map(|line| line.split(",").map(String::from).collect())
@@ -54,32 +64,49 @@ fn closest(input: String) -> Option<i32> {
     entries[0]
         .intersection(&entries[1])
         .cloned()
-        .map(distance)
+        .map(|c| (c.1).0.abs() + (c.1).1.abs())
         .min()
 }
 
-fn first(input: String) -> Option<i32> {}
+fn first(input: &str) -> Option<i32> {
+    let entries: Vec<BTreeSet<Coord>> = input
+        .trim()
+        .split("\n")
+        .map(|line| line.split(",").map(String::from).collect())
+        .map(to_coordinates)
+        .collect();
+
+    entries[0]
+        .intersection(&entries[1])
+        .cloned()
+        .map(|c| {
+            let other = entries[1].get(&c);
+            (c.0 + other.unwrap().0) as i32
+        })
+        .min()
+}
 
 pub fn main() -> io::Result<()> {
-    let closest = closest(std::include_str!("../day3-input.txt").to_owned());
-    println!("{:?}", closest);
+    let input = std::include_str!("../day3-input.txt");
+    println!("{:?}", closest(input));
+    println!("{:?}", first(input));
 
     Ok(())
 }
 
 #[test]
 fn test_coordinates_for_entry() {
-    let mut expected: BTreeSet<(i32, i32)> = BTreeSet::new();
+    let mut expected: BTreeSet<Coord> = BTreeSet::new();
     for i in 1..11 {
-        expected.insert((i, 0));
+        expected.insert(Coord(i - 1, (i as i32, 0)));
     }
     assert_eq!(to_coordinates(vec!["R10".to_owned()]), expected);
 
     expected = BTreeSet::new();
-    expected.insert((1, 0));
-    expected.insert((2, 0));
-    expected.insert((2, 1));
-    expected.insert((2, 2));
+    expected.insert(Coord(0, (1, 0)));
+    expected.insert(Coord(1, (2, 0)));
+    expected.insert(Coord(2, (2, 1)));
+    expected.insert(Coord(3, (2, 2)));
     let input = "R2,U2".to_owned().split(",").map(String::from).collect();
     assert_eq!(to_coordinates(input), expected);
 }
@@ -87,11 +114,19 @@ fn test_coordinates_for_entry() {
 #[test]
 fn test_part_one() {
     let input = "R75,D30,R83,U83,L12,D49,R71,U7,L72\n\
-                 U62,R66,U55,R34,D71,R55,D58,R83"
-        .to_owned();
+                 U62,R66,U55,R34,D71,R55,D58,R83";
     assert_eq!(closest(input), Some(159));
     let input = "R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51\n\
-                 U98,R91,D20,R16,D67,R40,U7,R15,U6,R7"
-        .to_owned();
+                 U98,R91,D20,R16,D67,R40,U7,R15,U6,R7";
     assert_eq!(closest(input), Some(135));
 }
+
+#[test]
+fn test_part_two() {
+    let input = "R75,D30,R83,U83,L12,D49,R71,U7,L72\n\
+                 U62,R66,U55,R34,D71,R55,D58,R83";
+    assert_eq!(first(input), Some(610));
+    let input = "R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51\n\
+                 U98,R91,D20,R16,D67,R40,U7,R15,U6,R7";
+    assert_eq!(first(input), Some(464));
+}