From 38a024d095565f139277b3ab95a4f7cab0134b41 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Mon, 5 Dec 2022 11:08:54 +0100
Subject: [PATCH] Implement 2022 day 5

---
 2022/benches/days.rs    |   2 +-
 2022/inputs/05.txt      | 514 ++++++++++++++++++++++++++++++++++++++++
 2022/src/day05.rs       | 168 ++++++++++++-
 2022/src/samples/05.txt |   9 +
 4 files changed, 688 insertions(+), 5 deletions(-)
 create mode 100644 2022/inputs/05.txt
 create mode 100644 2022/src/samples/05.txt

diff --git a/2022/benches/days.rs b/2022/benches/days.rs
index 814e95e..77e9853 100644
--- a/2022/benches/days.rs
+++ b/2022/benches/days.rs
@@ -8,7 +8,7 @@ use criterion::BenchmarkId;
 use criterion::Criterion;
 
 /// Number of days we have an implementation to benchmark
-const DAYS_IMPLEMENTED: u8 = 4;
+const DAYS_IMPLEMENTED: u8 = 5;
 
 fn read_input(day: u8) -> Vec<u8> {
     let input_path = format!("inputs/{:02}.txt", day);
diff --git a/2022/inputs/05.txt b/2022/inputs/05.txt
new file mode 100644
index 0000000..8d7a981
--- /dev/null
+++ b/2022/inputs/05.txt
@@ -0,0 +1,514 @@
+        [G]         [D]     [Q]    
+[P]     [T]         [L] [M] [Z]    
+[Z] [Z] [C]         [Z] [G] [W]    
+[M] [B] [F]         [P] [C] [H] [N]
+[T] [S] [R]     [H] [W] [R] [L] [W]
+[R] [T] [Q] [Z] [R] [S] [Z] [F] [P]
+[C] [N] [H] [R] [N] [H] [D] [J] [Q]
+[N] [D] [M] [G] [Z] [F] [W] [S] [S]
+ 1   2   3   4   5   6   7   8   9 
+
+move 7 from 6 to 8
+move 5 from 2 to 6
+move 2 from 4 to 1
+move 1 from 4 to 5
+move 5 from 7 to 6
+move 7 from 6 to 3
+move 5 from 9 to 2
+move 6 from 2 to 3
+move 2 from 7 to 9
+move 20 from 3 to 1
+move 11 from 1 to 6
+move 1 from 9 to 8
+move 3 from 8 to 2
+move 8 from 1 to 5
+move 10 from 8 to 4
+move 7 from 6 to 4
+move 1 from 8 to 3
+move 8 from 1 to 7
+move 16 from 4 to 8
+move 1 from 9 to 8
+move 1 from 5 to 2
+move 4 from 7 to 4
+move 5 from 6 to 7
+move 1 from 6 to 1
+move 8 from 7 to 4
+move 1 from 6 to 9
+move 12 from 4 to 5
+move 3 from 2 to 5
+move 1 from 6 to 2
+move 1 from 3 to 7
+move 1 from 3 to 2
+move 1 from 9 to 3
+move 1 from 7 to 8
+move 1 from 7 to 5
+move 1 from 3 to 2
+move 4 from 5 to 7
+move 5 from 5 to 7
+move 1 from 4 to 3
+move 1 from 3 to 9
+move 3 from 1 to 8
+move 1 from 9 to 1
+move 2 from 2 to 1
+move 2 from 2 to 7
+move 8 from 8 to 1
+move 3 from 5 to 2
+move 8 from 7 to 5
+move 7 from 1 to 3
+move 3 from 1 to 7
+move 1 from 1 to 5
+move 1 from 3 to 7
+move 7 from 5 to 8
+move 2 from 2 to 8
+move 1 from 3 to 2
+move 1 from 2 to 4
+move 1 from 4 to 8
+move 13 from 8 to 1
+move 13 from 5 to 9
+move 2 from 5 to 2
+move 7 from 9 to 3
+move 12 from 8 to 3
+move 4 from 9 to 3
+move 1 from 3 to 4
+move 2 from 2 to 3
+move 1 from 1 to 6
+move 1 from 2 to 3
+move 1 from 5 to 9
+move 7 from 7 to 4
+move 10 from 1 to 8
+move 1 from 1 to 4
+move 1 from 9 to 5
+move 2 from 5 to 1
+move 1 from 6 to 5
+move 3 from 8 to 9
+move 5 from 4 to 3
+move 4 from 4 to 1
+move 7 from 1 to 6
+move 2 from 5 to 7
+move 35 from 3 to 4
+move 4 from 9 to 1
+move 19 from 4 to 8
+move 1 from 7 to 6
+move 1 from 9 to 2
+move 10 from 4 to 5
+move 2 from 4 to 7
+move 3 from 4 to 3
+move 1 from 2 to 8
+move 1 from 1 to 9
+move 3 from 3 to 6
+move 4 from 8 to 6
+move 4 from 5 to 2
+move 2 from 8 to 3
+move 3 from 5 to 9
+move 12 from 6 to 1
+move 8 from 8 to 6
+move 2 from 9 to 1
+move 1 from 4 to 1
+move 1 from 3 to 8
+move 3 from 7 to 8
+move 2 from 9 to 7
+move 1 from 6 to 7
+move 10 from 6 to 8
+move 4 from 2 to 5
+move 1 from 3 to 7
+move 7 from 5 to 7
+move 13 from 8 to 1
+move 29 from 1 to 4
+move 8 from 7 to 8
+move 1 from 1 to 3
+move 3 from 7 to 6
+move 1 from 1 to 9
+move 15 from 4 to 1
+move 1 from 3 to 6
+move 10 from 1 to 6
+move 10 from 6 to 7
+move 1 from 4 to 9
+move 1 from 9 to 1
+move 1 from 9 to 7
+move 6 from 7 to 8
+move 1 from 1 to 6
+move 5 from 6 to 5
+move 21 from 8 to 9
+move 5 from 1 to 9
+move 2 from 9 to 5
+move 3 from 5 to 6
+move 3 from 7 to 9
+move 4 from 4 to 6
+move 6 from 8 to 7
+move 6 from 6 to 3
+move 2 from 7 to 9
+move 1 from 7 to 2
+move 6 from 3 to 2
+move 1 from 6 to 4
+move 4 from 5 to 9
+move 1 from 4 to 5
+move 9 from 4 to 6
+move 7 from 6 to 4
+move 10 from 9 to 2
+move 5 from 7 to 5
+move 10 from 2 to 7
+move 2 from 5 to 4
+move 2 from 5 to 9
+move 4 from 9 to 4
+move 1 from 8 to 6
+move 7 from 7 to 2
+move 1 from 5 to 4
+move 2 from 7 to 1
+move 1 from 5 to 7
+move 3 from 6 to 2
+move 4 from 4 to 5
+move 1 from 2 to 7
+move 10 from 4 to 7
+move 3 from 7 to 3
+move 17 from 9 to 4
+move 1 from 1 to 4
+move 1 from 1 to 5
+move 5 from 2 to 7
+move 1 from 9 to 2
+move 5 from 4 to 8
+move 2 from 9 to 7
+move 4 from 8 to 1
+move 3 from 4 to 8
+move 1 from 2 to 5
+move 1 from 9 to 2
+move 6 from 4 to 8
+move 3 from 7 to 5
+move 1 from 4 to 9
+move 1 from 9 to 1
+move 3 from 1 to 9
+move 4 from 8 to 5
+move 2 from 9 to 8
+move 4 from 2 to 5
+move 8 from 7 to 2
+move 5 from 8 to 5
+move 2 from 7 to 8
+move 1 from 3 to 5
+move 1 from 1 to 2
+move 1 from 1 to 6
+move 2 from 3 to 6
+move 5 from 2 to 8
+move 4 from 7 to 1
+move 7 from 8 to 5
+move 1 from 1 to 5
+move 3 from 8 to 3
+move 1 from 9 to 3
+move 7 from 2 to 3
+move 2 from 2 to 8
+move 2 from 4 to 8
+move 1 from 8 to 5
+move 1 from 1 to 4
+move 2 from 4 to 7
+move 2 from 7 to 1
+move 3 from 2 to 3
+move 3 from 5 to 2
+move 1 from 8 to 3
+move 3 from 3 to 2
+move 5 from 2 to 1
+move 17 from 5 to 8
+move 9 from 8 to 1
+move 11 from 3 to 5
+move 8 from 8 to 5
+move 2 from 8 to 5
+move 16 from 1 to 4
+move 13 from 4 to 7
+move 6 from 5 to 2
+move 2 from 4 to 8
+move 5 from 7 to 9
+move 2 from 1 to 2
+move 7 from 7 to 1
+move 1 from 1 to 4
+move 1 from 9 to 8
+move 7 from 2 to 8
+move 1 from 4 to 7
+move 2 from 9 to 4
+move 1 from 4 to 1
+move 1 from 3 to 5
+move 2 from 9 to 8
+move 11 from 8 to 7
+move 2 from 6 to 5
+move 1 from 6 to 9
+move 1 from 1 to 9
+move 1 from 9 to 1
+move 4 from 1 to 4
+move 2 from 1 to 8
+move 1 from 1 to 2
+move 1 from 9 to 5
+move 2 from 4 to 3
+move 2 from 2 to 7
+move 2 from 3 to 9
+move 1 from 9 to 1
+move 1 from 9 to 1
+move 5 from 5 to 1
+move 19 from 5 to 6
+move 5 from 1 to 4
+move 1 from 2 to 9
+move 1 from 1 to 3
+move 7 from 5 to 8
+move 1 from 3 to 6
+move 8 from 7 to 3
+move 7 from 4 to 8
+move 3 from 8 to 5
+move 1 from 4 to 1
+move 1 from 9 to 4
+move 1 from 4 to 9
+move 1 from 5 to 2
+move 2 from 5 to 6
+move 2 from 8 to 2
+move 7 from 8 to 1
+move 1 from 1 to 7
+move 3 from 6 to 9
+move 2 from 3 to 2
+move 1 from 2 to 1
+move 1 from 8 to 7
+move 2 from 9 to 6
+move 2 from 9 to 5
+move 1 from 5 to 6
+move 1 from 2 to 8
+move 2 from 1 to 7
+move 1 from 4 to 3
+move 3 from 2 to 5
+move 7 from 1 to 3
+move 10 from 3 to 4
+move 3 from 5 to 4
+move 1 from 3 to 8
+move 3 from 3 to 2
+move 1 from 8 to 1
+move 1 from 1 to 3
+move 3 from 8 to 3
+move 5 from 4 to 6
+move 1 from 2 to 3
+move 4 from 6 to 4
+move 1 from 5 to 7
+move 4 from 3 to 4
+move 1 from 2 to 8
+move 12 from 7 to 6
+move 1 from 8 to 2
+move 2 from 2 to 7
+move 1 from 8 to 4
+move 23 from 6 to 3
+move 14 from 3 to 6
+move 15 from 4 to 6
+move 1 from 8 to 6
+move 10 from 3 to 7
+move 2 from 4 to 2
+move 11 from 7 to 8
+move 2 from 2 to 6
+move 44 from 6 to 9
+move 21 from 9 to 3
+move 12 from 3 to 6
+move 1 from 7 to 4
+move 1 from 4 to 7
+move 9 from 3 to 2
+move 2 from 8 to 6
+move 3 from 2 to 4
+move 17 from 9 to 1
+move 3 from 4 to 6
+move 2 from 2 to 9
+move 4 from 9 to 2
+move 10 from 6 to 9
+move 1 from 7 to 6
+move 4 from 9 to 5
+move 4 from 2 to 4
+move 14 from 1 to 5
+move 4 from 4 to 3
+move 3 from 2 to 9
+move 9 from 9 to 7
+move 1 from 2 to 5
+move 9 from 8 to 5
+move 8 from 7 to 2
+move 4 from 3 to 8
+move 5 from 6 to 2
+move 3 from 1 to 6
+move 1 from 7 to 1
+move 4 from 2 to 4
+move 3 from 6 to 4
+move 3 from 8 to 3
+move 13 from 5 to 2
+move 2 from 3 to 5
+move 12 from 5 to 9
+move 1 from 3 to 5
+move 1 from 5 to 9
+move 1 from 8 to 3
+move 4 from 9 to 5
+move 6 from 4 to 5
+move 12 from 9 to 7
+move 1 from 9 to 3
+move 1 from 3 to 2
+move 12 from 5 to 6
+move 12 from 7 to 2
+move 1 from 3 to 7
+move 1 from 4 to 8
+move 33 from 2 to 8
+move 1 from 7 to 5
+move 1 from 1 to 2
+move 4 from 5 to 4
+move 3 from 2 to 5
+move 34 from 8 to 6
+move 1 from 4 to 3
+move 1 from 5 to 7
+move 1 from 7 to 5
+move 3 from 4 to 9
+move 2 from 9 to 7
+move 1 from 9 to 4
+move 1 from 3 to 7
+move 1 from 5 to 8
+move 1 from 5 to 1
+move 1 from 5 to 7
+move 1 from 4 to 8
+move 1 from 1 to 4
+move 1 from 4 to 2
+move 3 from 7 to 5
+move 2 from 8 to 5
+move 1 from 2 to 8
+move 4 from 6 to 2
+move 1 from 8 to 6
+move 1 from 7 to 9
+move 29 from 6 to 7
+move 4 from 2 to 3
+move 2 from 5 to 8
+move 1 from 9 to 5
+move 2 from 8 to 1
+move 23 from 7 to 5
+move 2 from 6 to 1
+move 23 from 5 to 6
+move 1 from 3 to 6
+move 4 from 5 to 9
+move 2 from 1 to 3
+move 5 from 3 to 8
+move 2 from 6 to 5
+move 2 from 1 to 4
+move 1 from 9 to 8
+move 1 from 9 to 1
+move 1 from 4 to 6
+move 2 from 5 to 6
+move 6 from 7 to 8
+move 2 from 9 to 2
+move 18 from 6 to 5
+move 21 from 6 to 4
+move 1 from 1 to 6
+move 2 from 6 to 7
+move 2 from 7 to 9
+move 2 from 2 to 8
+move 7 from 4 to 3
+move 12 from 5 to 3
+move 1 from 9 to 5
+move 1 from 9 to 4
+move 6 from 5 to 2
+move 17 from 3 to 4
+move 3 from 4 to 3
+move 1 from 2 to 4
+move 5 from 2 to 8
+move 1 from 5 to 8
+move 19 from 8 to 7
+move 1 from 3 to 6
+move 1 from 8 to 4
+move 1 from 6 to 1
+move 15 from 4 to 6
+move 1 from 1 to 4
+move 3 from 3 to 5
+move 4 from 6 to 7
+move 1 from 4 to 7
+move 10 from 6 to 7
+move 16 from 4 to 5
+move 24 from 7 to 2
+move 8 from 7 to 8
+move 1 from 4 to 2
+move 6 from 8 to 7
+move 1 from 8 to 7
+move 1 from 6 to 9
+move 14 from 5 to 4
+move 9 from 7 to 8
+move 4 from 5 to 1
+move 2 from 1 to 5
+move 3 from 8 to 6
+move 2 from 6 to 9
+move 2 from 2 to 8
+move 6 from 2 to 7
+move 3 from 4 to 6
+move 1 from 3 to 4
+move 3 from 5 to 7
+move 1 from 6 to 9
+move 5 from 7 to 2
+move 4 from 9 to 1
+move 1 from 7 to 9
+move 9 from 8 to 4
+move 5 from 1 to 2
+move 2 from 6 to 1
+move 6 from 4 to 7
+move 1 from 7 to 3
+move 1 from 3 to 9
+move 1 from 9 to 7
+move 1 from 6 to 7
+move 9 from 4 to 5
+move 7 from 7 to 9
+move 3 from 7 to 5
+move 1 from 9 to 2
+move 6 from 9 to 8
+move 4 from 4 to 5
+move 1 from 4 to 2
+move 1 from 4 to 2
+move 2 from 1 to 2
+move 1 from 9 to 8
+move 10 from 2 to 4
+move 8 from 2 to 7
+move 12 from 2 to 9
+move 6 from 7 to 4
+move 1 from 1 to 2
+move 8 from 9 to 8
+move 7 from 5 to 1
+move 9 from 4 to 3
+move 14 from 8 to 4
+move 1 from 8 to 4
+move 1 from 1 to 5
+move 1 from 5 to 2
+move 3 from 2 to 4
+move 1 from 7 to 1
+move 1 from 7 to 3
+move 2 from 1 to 7
+move 3 from 5 to 7
+move 2 from 7 to 6
+move 1 from 6 to 5
+move 3 from 7 to 1
+move 1 from 6 to 8
+move 1 from 8 to 7
+move 1 from 3 to 6
+move 1 from 7 to 1
+move 4 from 1 to 4
+move 6 from 3 to 2
+move 3 from 1 to 2
+move 3 from 3 to 6
+move 3 from 2 to 6
+move 6 from 6 to 5
+move 1 from 1 to 4
+move 1 from 9 to 6
+move 5 from 2 to 1
+move 3 from 1 to 2
+move 2 from 9 to 8
+move 3 from 1 to 5
+move 1 from 9 to 7
+move 25 from 4 to 1
+move 1 from 1 to 7
+move 2 from 8 to 3
+move 13 from 1 to 9
+move 2 from 3 to 5
+move 8 from 5 to 9
+move 4 from 2 to 1
+move 2 from 6 to 7
+move 10 from 5 to 9
+move 4 from 7 to 2
+move 2 from 2 to 3
+move 9 from 9 to 2
+move 4 from 4 to 5
+move 4 from 5 to 4
+move 5 from 1 to 4
+move 10 from 4 to 5
+move 22 from 9 to 1
+move 2 from 2 to 7
+move 3 from 2 to 1
+move 6 from 2 to 6
+move 1 from 7 to 1
+move 10 from 5 to 7
+move 15 from 1 to 4
+move 13 from 1 to 5
+move 3 from 6 to 8
+move 1 from 8 to 9
diff --git a/2022/src/day05.rs b/2022/src/day05.rs
index 745aff3..83960cc 100644
--- a/2022/src/day05.rs
+++ b/2022/src/day05.rs
@@ -1,9 +1,169 @@
+use std::cmp::Ordering;
+
 use anyhow::Result;
+use nom::branch::alt;
+use nom::bytes::complete::tag;
+use nom::bytes::complete::take;
+use nom::bytes::complete::take_until;
+use nom::character::complete::newline;
+use nom::combinator::map;
+use nom::combinator::opt;
+use nom::multi::fold_many1;
+use nom::multi::many1;
+use nom::sequence::delimited;
+use nom::sequence::preceded;
+use nom::sequence::terminated;
+use nom::sequence::tuple;
+use nom::IResult;
 
-pub fn part1(_input: &[u8]) -> Result<String> {
-    todo!()
+use crate::common::parse_input;
+
+type Move = (usize, usize, usize);
+type OwnedStacks = Vec<Vec<u8>>;
+
+fn parse_row<'a>(input: &'a [u8], stacks: &mut OwnedStacks) -> IResult<&'a [u8], ()> {
+    let mut index = 0usize;
+
+    // Forgive me for this crime
+    fold_many1(
+        terminated(
+            alt((
+                // Parse a delimited value into a Some(content)
+                map(delimited(tag("["), take(1usize), tag("]")), |v: &[u8]| {
+                    Some(v[0])
+                }),
+                // Or an empty stack into a None
+                map(tag("   "), |_| None),
+            )),
+            opt(tag(" ")),
+        ),
+        || (),
+        move |_, c| {
+            if let Some(b) = c {
+                if stacks.len() <= index {
+                    stacks.resize_with(index + 1, Vec::new);
+                }
+
+                stacks[index].push(b)
+            }
+
+            index += 1;
+        },
+    )(input)
 }
 
-pub fn part2(_input: &[u8]) -> Result<String> {
-    todo!()
+fn parse_stacks(input: &[u8]) -> IResult<&[u8], OwnedStacks> {
+    let mut stacks = Vec::new();
+
+    let (input, _) = terminated(
+        fold_many1(
+            terminated(|input| parse_row(input, &mut stacks), newline),
+            || (),
+            |_, _| (),
+        ),
+        // Skip the line with the numbers
+        take_until("\n\n"),
+    )(input)?;
+
+    // Reverse the stacks since we parsed them top-down
+    for stack in &mut stacks {
+        stack.reverse();
+    }
+
+    Ok((input, stacks))
+}
+
+fn parse_task(input: &[u8]) -> IResult<&[u8], (OwnedStacks, Vec<Move>)> {
+    fn parse_usize(input: &[u8]) -> IResult<&[u8], usize> {
+        map(nom::character::complete::u32, |v| v as usize)(input)
+    }
+    let (input, stacks) = parse_stacks(input)?;
+
+    // Consume the double newline
+    let (input, _) = tag("\n\n")(input)?;
+
+    let (input, moves) = many1(terminated(
+        tuple((
+            preceded(tag("move "), parse_usize),
+            preceded(tag(" from "), parse_usize),
+            preceded(tag(" to "), parse_usize),
+        )),
+        newline,
+    ))(input)?;
+
+    Ok((input, (stacks, moves)))
+}
+
+/// Some magic to get two mutable references into the same slice
+fn get_both(stacks: &mut [Vec<u8>], from: usize, to: usize) -> (&mut Vec<u8>, &mut Vec<u8>) {
+    match from.cmp(&to) {
+        Ordering::Greater => {
+            let (begin, end) = stacks.split_at_mut(from);
+            (&mut end[0], &mut begin[to])
+        }
+        Ordering::Less => {
+            let (begin, end) = stacks.split_at_mut(to);
+            (&mut begin[from], &mut end[0])
+        }
+        Ordering::Equal => panic!("Tried to stack from and to {from}"),
+    }
+}
+
+fn compute_answer(stacks: &mut [Vec<u8>]) -> Result<String> {
+    let mut result = String::with_capacity(stacks.len());
+
+    for stack in stacks {
+        result.push(
+            *stack
+                .last()
+                .ok_or_else(|| anyhow::anyhow!("Encountered empty stack"))? as char,
+        );
+    }
+
+    Ok(result)
+}
+
+pub fn part1(input: &[u8]) -> Result<String> {
+    let (mut stacks, moves) = parse_input(input, parse_task)?;
+
+    for (count, from, to) in moves {
+        let (from, to) = get_both(&mut stacks, from - 1, to - 1);
+
+        let drain_start = from.len() - count;
+
+        to.extend(from.drain(drain_start..).rev());
+    }
+
+    compute_answer(&mut stacks)
+}
+
+pub fn part2(input: &[u8]) -> Result<String> {
+    let (mut stacks, moves) = parse_input(input, parse_task)?;
+
+    for (count, from, to) in moves {
+        let (from, to) = get_both(&mut stacks, from - 1, to - 1);
+
+        let drain_start = from.len() - count;
+
+        to.extend(from.drain(drain_start..));
+    }
+
+    compute_answer(&mut stacks)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const SAMPLE: &[u8] = include_bytes!("samples/05.txt");
+
+    #[test]
+    fn sample_part1() {
+        assert_eq!(part1(SAMPLE).unwrap(), "CMZ");
+    }
+
+    #[test]
+    fn sample_part2() {
+        assert_eq!(part2(SAMPLE).unwrap(), "MCD");
+    }
 }
diff --git a/2022/src/samples/05.txt b/2022/src/samples/05.txt
new file mode 100644
index 0000000..84933bb
--- /dev/null
+++ b/2022/src/samples/05.txt
@@ -0,0 +1,9 @@
+    [D]    
+[N] [C]    
+[Z] [M] [P]
+ 1   2   3 
+
+move 1 from 2 to 1
+move 3 from 1 to 3
+move 2 from 2 to 1
+move 1 from 1 to 2