day(05): add initial version

Signed-off-by: Matej Focko <mfocko@redhat.com>

samples/day05.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

src/bin/day05.rs

@@ -0,0 +1,155 @@
+use std::cmp::max;
+use std::str::FromStr;
+
+use aoc_2022::*;
+
+use color_eyre::eyre::{Report, Result};
+use itertools::Itertools;
+use tracing::*;
+use tracing_subscriber::EnvFilter;
+
+#[derive(Debug)]
+struct Move {
+    count: usize,
+    from: usize,
+    to: usize,
+}
+
+impl FromStr for Move {
+    type Err = Report;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let split_str: Vec<_> = s.split_whitespace().collect();
+        let ints = vec![split_str[1], split_str[3], split_str[5]]
+            .iter()
+            .map(|x| x.parse::<usize>().unwrap())
+            .collect_vec();
+
+        let (count, from, to) = (ints[0], ints[1], ints[2]);
+
+        Ok(Move { count, from, to })
+    }
+}
+
+#[derive(Debug)]
+struct Ship(Vec<Vec<char>>, Vec<Move>);
+
+impl FromStr for Ship {
+    type Err = Report;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let split_s = s.split("\n\n").collect_vec();
+        let (stacks_str, moves_str) = (split_s[0], split_s[1]);
+
+        let mut stacks: Vec<Vec<char>> = Vec::new();
+
+        stacks_str
+            .lines()
+            .rev()
+            .skip(1)
+            .map(|l| l.to_string() + " ")
+            .for_each(|l| {
+                l.chars().skip(1).step_by(4).enumerate().for_each(|(i, c)| {
+                    if i >= stacks.len() {
+                        stacks.push(Vec::new());
+                    }
+
+                    if c != ' ' {
+                        stacks[i].push(c);
+                    }
+                });
+            });
+
+        let moves = strings_to_structs(moves_str.lines());
+
+        Ok(Ship(stacks, moves))
+    }
+}
+
+type Input = Ship;
+type Output = String;
+
+fn part_1(input: &Input) -> Output {
+    let Ship(stacks, moves) = input;
+
+    let mut stacks = stacks.clone();
+
+    moves.iter().for_each(|m| {
+        for _ in 0..m.count {
+            if stacks[m.from - 1].is_empty() {
+                break;
+            }
+
+            let popped = stacks[m.from - 1].pop().unwrap();
+            stacks[m.to - 1].push(popped);
+        }
+    });
+
+    stacks.iter().fold(String::new(), |acc, stack| {
+        if let Some(c) = stack.last() {
+            acc + &c.to_string()
+        } else {
+            acc
+        }
+    })
+}
+
+fn part_2(input: &Input) -> Output {
+    let Ship(stacks, moves) = input;
+
+    let mut stacks = stacks.clone();
+
+    moves.iter().for_each(|m| {
+        let size = stacks[m.from - 1].len();
+        let mut s = stacks[m.from - 1].split_off(max(0, size - m.count));
+        stacks[m.to - 1].append(&mut s);
+    });
+
+    stacks.iter().fold(String::new(), |acc, stack| {
+        if let Some(c) = stack.last() {
+            acc + &c.to_string()
+        } else {
+            acc
+        }
+    })
+}
+
+fn parse_input(pathname: &str) -> Input {
+    file_to_string(pathname).parse::<Input>().unwrap()
+}
+
+fn main() -> Result<()> {
+    tracing_subscriber::fmt()
+        .with_env_filter(EnvFilter::from_default_env())
+        .with_target(false)
+        .with_file(true)
+        .with_line_number(true)
+        .without_time()
+        .compact()
+        .init();
+    color_eyre::install()?;
+
+    let input = parse_input("inputs/day05.txt");
+
+    info!("Part 1: {}", part_1(&input));
+    info!("Part 2: {}", part_2(&input));
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod day_05 {
+    use super::*;
+
+    #[test]
+    fn test_part_1() {
+        let sample = parse_input("samples/day05.txt");
+        assert_eq!(part_1(&sample), "CMZ".to_string());
+    }
+
+    #[test]
+    fn test_part_2() {
+        let sample = parse_input("samples/day05.txt");
+        assert_eq!(part_2(&sample), "MCD".to_string());
+    }
+}