From: Grégory Burri <gregory.burri@matisa.ch>
Date: Wed, 4 Dec 2019 07:54:44 +0000 (+0100)
Subject: Day03 - part 1
X-Git-Url: https://git.euphorik.ch/?a=commitdiff_plain;h=ad906a5049a043bb522252ad02bd9cca7422be44;p=advent_of_code_2019.git

Day03 - part 1
---

diff --git a/src/day02.rs b/src/day02.rs
index 76bc33e..9db5379 100644
--- a/src/day02.rs
+++ b/src/day02.rs
@@ -19,8 +19,8 @@ fn execute_op_code(code : &mut [i32]) -> i32 {
 
 pub fn find_noun_and_verb(code : &[i32]) -> i32 {
     loop {
-        for noun in 0..=99 {
-            for verb in 0..=99 {
+        for verb in 0..=99 {
+            for noun in 0..=99 {
                 let mut code_copy = Vec::from(code);
                 code_copy[1] = noun;
                 code_copy[2] = verb;
diff --git a/src/day03.rs b/src/day03.rs
new file mode 100644
index 0000000..a35ce3f
--- /dev/null
+++ b/src/day03.rs
@@ -0,0 +1,59 @@
+use std::iter::Iterator;
+use std::collections::HashSet;
+
+pub fn split_movements(movements: &str) -> Vec<&str> {
+    movements.split(',').collect()
+}
+
+pub fn manhattan_distance_from_cross_to_port(wire1: &[&str], wire2: &[&str]) -> i32 {
+    fn positions(wire: &[&str]) -> HashSet<(i32, i32)> {
+        let (mut x, mut y) = (0, 0);
+        let mut pos = HashSet::<(i32, i32)>::new();
+        for mov in wire {
+            let distance = mov[1..].parse::<i32>().unwrap();
+            match mov.chars().nth(0).unwrap() {
+                'U'      => { for y2 in y+1 ..= y + distance { pos.insert((x, y2)); } y += distance },
+                'D'      => { for y2 in y - distance .. y    { pos.insert((x, y2)); } y -= distance },
+                'R'      => { for x2 in x+1 ..= x + distance { pos.insert((x2, y)); } x += distance },
+                'L' | _  => { for x2 in x - distance .. x    { pos.insert((x2, y)); } x -= distance },
+            }
+        }
+        pos
+    }
+
+    let (positions_wire1, positions_wire2) = (positions(wire1), positions(wire2));
+    let cross: HashSet<_> = positions_wire1.intersection(&positions_wire2).collect();
+    cross.iter().map(|(x, y)| x.abs() + y.abs()).min().unwrap()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn simple_cases() {
+        assert_eq!(
+            manhattan_distance_from_cross_to_port(
+                &split_movements("R8,U5,L5,D3"),
+                &split_movements("U7,R6,D4,L4")
+            ),
+            6
+        );
+
+        assert_eq!(
+            manhattan_distance_from_cross_to_port(
+                &split_movements("R75,D30,R83,U83,L12,D49,R71,U7,L72"),
+                &split_movements("U62,R66,U55,R34,D71,R55,D58,R83")
+            ),
+            159
+        );
+
+        assert_eq!(
+            manhattan_distance_from_cross_to_port(
+                &split_movements("R98,U47,R26,D63,R33,U87,L62,D20,R33,U53,R51"),
+                &split_movements("U98,R91,D20,R16,D67,R40,U7,R15,U6,R7")
+            ),
+            135
+        );
+    }
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index 83918d4..eff33ed 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,8 +1,10 @@
 use std::env;
+use std::fs;
 use std::time::Instant;
 
 mod day01;
 mod day02;
+mod day03;
 mod common;
 
 fn day01() -> String {
@@ -15,6 +17,15 @@ fn day02() -> String {
     format!("part1: {}, part2: {}", day02::execute_op_code_with_state_fixed(&mut Vec::from(&code[..])), day02::find_noun_and_verb(&code))
 }
 
+fn day03() -> String {
+    let file_content = fs::read_to_string("data/day03.input").unwrap();
+    let movements: Vec<&str> = file_content.lines().collect();
+    format!(
+        "part1: {}",
+        day03::manhattan_distance_from_cross_to_port(&day03::split_movements(&movements[0]), &day03::split_movements(&movements[1]))
+    )
+}
+
 fn do_day(days: &[fn() -> String], day: usize) {
     let now = Instant::now();
     println!("Result of day {}: {} (time: {} μs)", day, days[day - 1](), now.elapsed().as_micros());
@@ -25,7 +36,8 @@ fn main() {
 
     let days: Vec<fn() -> String> = vec!(
         day01,
-        day02
+        day02,
+        day03
     );
 
     let args: Vec<String> = env::args().skip(1).collect();