From aa9dab827f5e69541744bc2139459dcab80e6511 Mon Sep 17 00:00:00 2001
From: Joe Ardent <code@ardent.nebcorp.com>
Date: Wed, 8 Jan 2025 12:21:14 -0800
Subject: [PATCH] day11 part1 works, part2 not yet.
---
Cargo.lock | 4 +++
Cargo.toml | 2 +-
day11/Cargo.toml | 6 ++++
day11/src/main.rs | 82 +++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 93 insertions(+), 1 deletion(-)
create mode 100644 day11/Cargo.toml
create mode 100644 day11/src/main.rs
diff --git a/Cargo.lock b/Cargo.lock
index ee53bf0..185b8ef 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -60,6 +60,10 @@ version = "0.1.0"
name = "day10"
version = "0.1.0"
+[[package]]
+name = "day11"
+version = "0.1.0"
+
[[package]]
name = "memchr"
version = "2.7.4"
diff --git a/Cargo.toml b/Cargo.toml
index 5785a84..834a35e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
[workspace]
resolver = "2"
-members = ["day01", "day02", "day03", "day04", "day05", "day06", "day07", "day08", "day09", "day10"]
+members = ["day01", "day02", "day03", "day04", "day05", "day06", "day07", "day08", "day09", "day10", "day11"]
[workspace.dependencies]
winnow = "0.6"
diff --git a/day11/Cargo.toml b/day11/Cargo.toml
new file mode 100644
index 0000000..864e412
--- /dev/null
+++ b/day11/Cargo.toml
@@ -0,0 +1,6 @@
+[package]
+name = "day11"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
diff --git a/day11/src/main.rs b/day11/src/main.rs
new file mode 100644
index 0000000..5f19ef4
--- /dev/null
+++ b/day11/src/main.rs
@@ -0,0 +1,82 @@
+use std::collections::VecDeque;
+
+fn main() {
+ let input = std::fs::read_to_string("input").unwrap();
+ let stones = parse(&input);
+ println!("{}", pt1(&stones));
+ println!("{}", pt2(&stones));
+}
+
+fn pt1(stones: &[u128]) -> usize {
+ blink2(stones, 25)
+}
+
+fn pt2(stones: &[u128]) -> usize {
+ let mut total = 0;
+ for stone in stones {
+ total += blink2(&[*stone], 75);
+ }
+ total
+}
+
+fn blink2(stones: &[u128], blinks: usize) -> usize {
+ let mut stones = VecDeque::from_iter(stones.iter().copied());
+
+ for _blink in 0..blinks {
+ let mut rots = 0;
+ while rots < stones.len() {
+ let stone = stones[0];
+ let digits = stone.to_string();
+
+ match stone {
+ 0 => {
+ stones[0] = 1;
+ stones.rotate_left(1);
+ rots += 1;
+ }
+ _ if digits.len() % 2 == 0 => {
+ let mid = digits.len() / 2;
+ let left = digits[0..mid].parse().unwrap();
+ let right = digits[mid..].parse().unwrap();
+ stones[0] = left;
+ stones.rotate_left(1);
+ stones.push_front(right);
+ stones.rotate_left(1);
+ rots += 2;
+ }
+ _ => {
+ stones[0] = stone * 2024;
+ stones.rotate_left(1);
+ rots += 1;
+ }
+ }
+ }
+ stones.rotate_right(rots);
+ }
+ stones.len()
+}
+
+fn parse(input: &str) -> Vec<u128> {
+ input
+ .trim()
+ .split(' ')
+ .map(|v| v.parse().unwrap())
+ .collect()
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ #[test]
+ fn p1() {
+ let stones = parse("125 17");
+ assert_eq!(55312, pt1(&stones));
+ }
+
+ #[test]
+ fn p2() {
+ let stones = parse("125 17");
+ assert_eq!(22, blink2(&stones, 6));
+ }
+}