Partial / not complete impl

src/day_three.rs

@@ -1,6 +1,5 @@
 use std::collections::BTreeSet;
-use std::fs::File;
-use std::io::{self, BufRead, BufReader};
+use std::io;
 use std::iter::{repeat, successors};
 
 fn next(c: (i32, i32), direction: &str) -> (i32, i32) {
@@ -14,8 +13,6 @@ fn next(c: (i32, i32), direction: &str) -> (i32, i32) {
 }
 
 fn direction_length(entry: String) -> (String, usize) {
-    /// Creates a (direction, length) pair to later produce a string
-    /// on a direction with the given length. E.g. given "R10" the output of
     (
         entry.chars().nth(0).unwrap().to_string(),
         entry[1..].parse().unwrap(),
@@ -46,19 +43,25 @@ fn distance(position: (i32, i32)) -> i32 {
     position.0.abs() + position.1.abs()
 }
 
-pub fn main() -> io::Result<()> {
-    let f = BufReader::new(File::open("day3-input.txt")?);
-    let entries: Vec<BTreeSet<(i32, i32)>> = f
-        .lines()
-        .map(|line| line.unwrap().split(",").map(String::from).collect())
+fn closest(input: String) -> Option<i32> {
+    let entries: Vec<BTreeSet<(i32, i32)>> = input
+        .trim()
+        .split("\n")
+        .map(|line| line.split(",").map(String::from).collect())
         .map(to_coordinates)
         .collect();
 
-    let closest: Option<i32> = entries[0]
+    entries[0]
         .intersection(&entries[1])
         .cloned()
         .map(distance)
-        .min();
+        .min()
+}
+
+fn first(input: String) -> Option<i32> {}
+
+pub fn main() -> io::Result<()> {
+    let closest = closest(std::include_str!("../day3-input.txt").to_owned());
     println!("{:?}", closest);
 
     Ok(())
@@ -80,3 +83,15 @@ fn test_coordinates_for_entry() {
     let input = "R2,U2".to_owned().split(",").map(String::from).collect();
     assert_eq!(to_coordinates(input), expected);
 }
+
+#[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();
+    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();
+    assert_eq!(closest(input), Some(135));
+}