From cd901b2fc5b3ca615675fee434521a15ccbfb6f2 Mon Sep 17 00:00:00 2001
From: Sijmen Schoon <me@sijmenschoon.nl>
Date: Fri, 25 Dec 2020 02:15:25 +0100
Subject: [PATCH] rust(day23): Rust too

---
 .gitignore        |  2 ++
 rust/src/day23.rs | 91 +++++++++++++++++++++++++++++++++++++++++++++++
 rust/src/main.rs  | 10 ++++++
 3 files changed, 103 insertions(+)
 create mode 100644 rust/src/day23.rs

diff --git a/.gitignore b/.gitignore
index 35cb943..0c0ef96 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,6 @@
 rust/target
+callgrind.*
+*.prof
 
 c64/*.vs
 c64/*.prg
diff --git a/rust/src/day23.rs b/rust/src/day23.rs
new file mode 100644
index 0000000..74dfa80
--- /dev/null
+++ b/rust/src/day23.rs
@@ -0,0 +1,91 @@
+use std::{time::Duration, time::Instant};
+
+fn step(cups: &mut [u32], current_label: u32, min: u32, max: u32) -> u32 {
+    let a = cups[current_label as usize];
+    let b = cups[a as usize];
+    let c = cups[b as usize];
+
+    let picked_up = &[a, b, c];
+    cups[current_label as usize] = cups[c as usize];
+
+    let mut destination = current_label - 1;
+    if destination < min {
+        destination = max;
+    }
+
+    while picked_up.contains(&destination) {
+        destination -= 1;
+        if destination < min {
+            destination = max;
+        }
+    }
+
+    cups[c as usize] = cups[destination as usize];
+    cups[destination as usize] = a;
+    cups[current_label as usize]
+}
+
+fn part1(labels: &[u32]) -> Option<u32> {
+    let mut cups = vec![0; labels.len() + 1];
+    for i in 0..labels.len() {
+        cups[labels[i] as usize] = labels[(i + 1) % labels.len()];
+    }
+
+    let mut current = labels[0];
+    let min = labels.iter().min()?;
+    let max = labels.iter().max()?;
+    for _ in 0..100 {
+        current = step(&mut cups, current, *min, *max);
+    }
+
+    let mut result = 0;
+    let mut label = 1;
+    for _ in 0..8 {
+        label = cups[label as usize];
+        result = result * 10 + label;
+    }
+
+    Some(result)
+}
+
+fn part2(old_labels: &[u32]) -> Option<usize> {
+    let mut labels = Vec::from(old_labels);
+    labels.reserve(1_000_000);
+    labels.extend((*old_labels.iter().max()? + 1)..=1_000_000);
+
+    let cups = &mut [0; 1_000_001];
+    for i in 0..labels.len() {
+        cups[labels[i] as usize] = labels[(i + 1) % labels.len()];
+    }
+
+    let mut current = labels[0];
+    let min = labels.iter().min()?;
+    let max = labels.iter().max()?;
+    for _ in 0..10_000_000 {
+        current = step(cups, current, *min, *max);
+    }
+
+    let a = cups[1] as usize;
+    let b = cups[a as usize] as usize;
+    Some(a * b)
+}
+
+pub fn run(print: bool) -> Duration {
+    let file_string = std::fs::read_to_string("../inputs/23").unwrap();
+    let instant = Instant::now();
+
+    let labels: Vec<u32> = file_string
+        .trim()
+        .chars()
+        .map(|c| (c as u32 - '0' as u32))
+        .collect();
+
+    let part1 = part1(&labels).unwrap();
+    let part2 = part2(&labels).unwrap();
+
+    if print {
+        dbg!(part1, part2);
+    }
+
+    instant.elapsed()
+}
diff --git a/rust/src/main.rs b/rust/src/main.rs
index 0eabf38..bce626f 100644
--- a/rust/src/main.rs
+++ b/rust/src/main.rs
@@ -22,6 +22,11 @@ mod day17;
 use nop as day18;
 mod day19;
 use nop as day20;
+use nop as day21;
+use nop as day22;
+mod day23;
+use nop as day24;
+use nop as day25;
 
 fn main() {
     let days = [
@@ -45,6 +50,11 @@ fn main() {
         day18::run,
         day19::run,
         day20::run,
+        day21::run,
+        day22::run,
+        day23::run,
+        day24::run,
+        day25::run,
     ];
 
     if let Some(day) = std::env::args().nth(1) {