Rust day 13

Author: OrangeBacon

data/day13.txt

@@ -0,0 +1,2 @@
+1015292
+19,x,x,x,x,x,x,x,x,41,x,x,x,x,x,x,x,x,x,743,x,x,x,x,x,x,x,x,x,x,x,x,13,17,x,x,x,x,x,x,x,x,x,x,x,x,x,x,29,x,643,x,x,x,x,x,37,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,x,23

src/days/day13.rs

@@ -0,0 +1,70 @@
+use anyhow::Result;
+use libaoc::{aoc, AocResult};
+use std::time::Instant;
+
+#[aoc("3215", "1001569619313439")]
+pub fn solve(input: String) -> Result<AocResult> {
+    let parse = Instant::now();
+    let lines: Vec<_> = input.lines().collect();
+    let secs: usize = lines[0].parse().unwrap();
+    let buses: Vec<usize> = lines[1]
+        .split(',')
+        .map(|x| x.parse())
+        .filter(|x| x.is_ok())
+        .map(|x| x.unwrap())
+        .collect();
+    let all_buses: Vec<Option<(usize, usize)>> = lines[1]
+        .split(',')
+        .map(|x| x.parse())
+        .enumerate()
+        .map(|x| {
+            if x.1.is_ok() {
+                Some((x.0, x.1.unwrap()))
+            } else {
+                None
+            }
+        })
+        .collect();
+    let parse = parse.elapsed().as_secs_f64();
+
+    let t1 = Instant::now();
+    let mut current = secs;
+    loop {
+        if buses.iter().any(|x| current % x == 0) {
+            break;
+        }
+        current += 1;
+    }
+    let part1 = (current - secs) * buses.iter().find(|&&x| current % x == 0).unwrap();
+
+    let t1 = t1.elapsed().as_secs_f64();
+
+    let t2 = Instant::now();
+    let mut start = 0;
+    let mut increment = 1;
+    for bus in &all_buses {
+        if let Some(bus) = bus {
+            let index = bus.0;
+            let num = bus.1;
+            loop {
+                start += increment;
+                if (start + index) % num == 0 {
+                    break;
+                }
+            }
+            let mut new_increment = start;
+            loop {
+                new_increment += increment;
+                if (new_increment + index) % num == 0 {
+                    break;
+                }
+            }
+            increment = new_increment - start;
+        }
+    }
+    let part2 = start;
+
+    let t2 = t2.elapsed().as_secs_f64();
+
+    Ok(AocResult::new(part1, part2, parse, t1, t2))
+}

src/days/mod.rs

@@ -10,3 +10,4 @@ mod day09;
 mod day10;
 mod day11;
 mod day12;
+mod day13;