day two

01/main.rs

@@ -14,7 +14,7 @@ fn main() {
     println!(
         "p1: {}ms, p2: {}ms",
         part_one_duration.as_millis(),
-        part_two_duration.as_millis()
+        (part_two_duration - part_one_duration).as_millis()
     );
 }
 

02/main.rs

@@ -0,0 +1,70 @@
+#![allow(dead_code)]
+use std::fs::File;
+use std::io;
+use std::io::BufRead;
+use std::path::Path;
+use std::time::Instant;
+
+fn main() {
+    let now = Instant::now();
+    part_one();
+    let part_one_duration = now.elapsed();
+    part_two();
+    let part_two_duration = now.elapsed();
+    println!(
+        "p1: {}ms, p2: {}ms",
+        part_one_duration.as_millis(),
+        (part_two_duration - part_one_duration).as_millis()
+    );
+}
+
+fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
+where
+    P: AsRef<Path>,
+{
+    // note that this discards a final newline
+    let file = File::open(filename)?;
+    Ok(io::BufReader::new(file).lines())
+}
+
+fn part_one() {
+    if let Ok(lines) = read_lines("./inputs/input") {
+        let mut score = 0;
+        for line in lines {
+            let l = line.unwrap();
+            let them = l.chars().nth(0).unwrap() as u32 - 64;
+            let you = l.chars().nth(2).unwrap() as u32 - 87;
+            score += you;
+            // 1 is Rock
+            // 2 is Paper
+            // 3 is Scissors
+            if you == them {
+                score += 3;
+            } else if them == 1 && you == 2 {
+                score += 6
+            } else if them == 2 && you == 3 {
+                score += 6
+            } else if them == 3 && you == 1 {
+                score += 6
+            }
+        }
+        println!("{}", score)
+    }
+}
+
+fn part_two() {
+    if let Ok(lines) = read_lines("./inputs/input") {
+        let mut score = 0;
+        for line in lines {
+            let l = line.unwrap();
+            let them = l.chars().nth(0).unwrap() as u32 - 64;
+            let outcome = l.chars().nth(2).unwrap() as u32 - 87;
+            // 1 is Rock / you lose
+            // 2 is Paper / you tie
+            // 3 is Scissors / you win
+            // compute what you throw plus the score of the round
+            score += ((them + outcome) % 3) + 1 + (outcome - 1) * 3;
+        }
+        println!("{}", score)
+    }
+}

main.rs.tmpl

@@ -14,7 +14,7 @@ fn main() {
     println!(
         "p1: {}ms, p2: {}ms",
         part_one_duration.as_millis(),
-        part_two_duration.as_millis()
+        (part_two_duration - part_one_duration).as_millis()
     );
 }