Add day 3 part 2 in Rust

2019/03/src/main.rs

@@ -1,4 +1,4 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 use std::io::{self, BufRead};
 
 struct Movement {
@@ -15,7 +15,8 @@ impl Movement {
     }
 }
 
-fn make_step(x: &mut i32, y: &mut i32, dir: char) {
+fn make_step(x: &mut i32, y: &mut i32, steps: &mut i32, dir: char) {
+    *steps += 1;
     match dir {
         'U' => *y += 1,
         'D' => *y -= 1,
@@ -33,24 +34,33 @@ pub fn main() {
             .collect::<Vec<_>>()
     });
     let (first_wire, second_wire) = (input.next().unwrap(), input.next().unwrap());
-    let mut first_wire_positions = HashSet::new();
-    let (mut x, mut y) = (0, 0);
+    let mut first_wire_positions = HashMap::new();
+    let (mut x, mut y, mut steps) = (0, 0, 0);
     for m in first_wire {
         for _ in 0..m.distance {
-            make_step(&mut x, &mut y, m.direction);
-            first_wire_positions.insert((x, y));
+            make_step(&mut x, &mut y, &mut steps, m.direction);
+            first_wire_positions.insert((x, y), steps);
         }
     }
     x = 0;
     y = 0;
+    steps = 0;
     let mut intersections = HashMap::new();
     for m in second_wire {
         for _ in 0..m.distance {
-            make_step(&mut x, &mut y, m.direction);
-            if first_wire_positions.contains(&(x, y)) {
-                intersections.insert((x, y), 0);
-            }
+            make_step(&mut x, &mut y, &mut steps, m.direction);
+            first_wire_positions
+                .get(&(x, y))
+                .map(|s| intersections.insert((x, y), s + steps));
         }
     }
-    println!("Part 1: {}", intersections.keys().map(|(x, y)| x.abs() + y.abs()).min().unwrap());
+    println!(
+        "Part 1: {}",
+        intersections
+            .keys()
+            .map(|(x, y)| x.abs() + y.abs())
+            .min()
+            .unwrap()
+    );
+    println!("Part 2: {}", intersections.values().min().unwrap());
 }