2022 rust day 12 part 1

2022/rust/inputs/day12.txt

@@ -0,0 +1,41 @@
+abcccccccccaaaaaaaaaaccccccccccccaaaaaaaaccaaccccccccccccccccccccccccccccccccccccccccccccaaaaaa
+abccccccccccaaaaaaaaaccccccccccccaaaaaaaaaaaacccccccccccaacccacccccccccccccccccccccccccccaaaaaa
+abcccccccccccaaaaaaacccccccccccccaaaaaaaaaaaaaacccccccccaaacaacccccccccaaaccccccccccccccccaaaaa
+abccccccccccaaaaaaccccccccccccccaaaaaaaaaaaaaaaccccccccccaaaaaccccccccccaaacccccccccccccccccaaa
+abccccccccccaaaaaaaccccccccccccaaaaaaaaaaaaaacccccccccccaaaaaacccccccccaaaacccccccccccccccccaac
+abaaccaaccccaaccaaaccccccccaaaaaaaaaaaaaaacaaccccccccccaaaaaaaacccccccccaaalcccccccccccccccaaac
+abaaaaaacccccccccaaccccccccaaaaaacccaaaacccaaccccccccccaaaaaaaaccccccccalllllllcccccccccccccccc
+abaaaaaacccccccaaacccccccccaaaaccccccaaaccccaaaaacccccccccaacccccccaaaakllllllllcccccccaacccccc
+abaaaaaacccccccaaaacccccccccaacccccccaaaccccaaaaacccccccccaacccccccaakkklllpllllccccacaaacccccc
+abaaaaaaaccccccaaaaccccaaccccccccccccccccccaaaaaaccccccccccccccccccckkkkpppppplllcccaaaaaaacccc
+abaaaaaaacaaaccaaaaccaaaaaaccccccccccccccccaaaaaacccccccaaaccccckkkkkkkpppppppplllcddaaaaaacccc
+abcaaaacccaacccccccccaaaaaacccccaaaccccccccaaaaaacccccccaaaaccjkkkkkkkpppppuppplmmdddddaaaccccc
+abccaaaaaaaaaccccccccaaaaaaccccaaaaaacccccccaaacccccccccaaaajjjkkkkkrpppuuuuupppmmmdddddacccccc
+abccccaaaaaaaacccccccaaaaacccccaaaaaacccccccccccccccccccaaacjjjjrrrrrrppuuuuupqqmmmmmddddaccccc
+abccccaaaaaaaaacccccccaaaacccccaaaaaaccccccccccccccccccccccjjjrrrrrrrrpuuuxuvvqqqmmmmmddddccccc
+abccccaaaaaaaaacccccccccccccccccaaaaaccccaacccaccccccccaaccjjjrrrruuuuuuuxxyvvqqqqqmmmmmdddcccc
+abccccaaaaaaaacccccccccaaaccccccaacaaccccaaacaacccaaacaaaccjjjrrrtuuuuuuuxxyvvvqqqqqmmmmdddcccc
+abccaaaaaaaacccccccccccaaaaaccccccccccccccaaaaacccaaaaaaaccjjjrrttttxxxxxxyyvvvvvqqqqmmmmdeeccc
+abccaaaccaaaccccccccaacaaaaacccccccccccccaaaaaacccaaaaaacccjjjrrtttxxxxxxxyyvvvvvvvqqqmmmeeeccc
+abaaaaaaaaaacccaaaccaaaaaaaaaaaccaaaccccaaaaaaaacccaaaaaaaajjjqqrttxxxxxxxyyyyyyvvvqqqnnneeeccc
+SbaaaaaaaaccccaaaaccaaaaaaaaaaaaaaaaacccaaaaaaaaccaaaaaaaaacjjjqqtttxxxxEzzyyyyvvvvqqqnnneeeccc
+abcaaaaaacccccaaaaccccaaaaaaaccaaaaaaccccccaaccccaaaaaaaaaaciiiqqqtttxxxyyyyyyvvvvrrrnnneeecccc
+abcaaaaaacccccaaaacccaaaaaaaaccaaaaaaccccccaaccccaaacaaacccciiiqqqqttxxyyyyyywvvvrrrnnneeeecccc
+abcaaaaaaccccccccccccaaaaaaaaacaaaaacccccccccccccccccaaaccccciiiqqtttxxyyyyyywwrrrrnnnneeeccccc
+abcaaacaacccccaacccccaaaaaaaaacaaaaacccccccccccccccccaaaccccciiiqqttxxxywwyyywwrrrnnnneeecccccc
+abccccccccaaacaaccccccccccacccccccccccccccccccccccccccccccccciiqqqttxxwwwwwwywwrrrnnneeeccccccc
+abccaacccccaaaaaccccccccccccccccccccccccccccccccccccccccaacaaiiqqqttwwwwsswwwwwrrrnnfffeccccccc
+abaaaaccccccaaaaaacccccccccccccccccccccccccccccaaaccccccaaaaaiiqqqttssssssswwwwrrronfffaccccccc
+abaaaaaacccaaaaaaacccccccccccccccccccccccccccaaaaaacccccaaaaaiiqqqssssssssssswrrrooofffaaaacccc
+abaaaaaaccaaaaaacccccccccccccccccccccccccccccaaaaaacccccaaaaaiiqqqppssspppssssrrrooofffaaaacccc
+abaaaaaaccaacaaacccccccccccccccccccccccccccccaaaaaacccccaaaaaiihpppppppppppossrrooofffaaaaacccc
+abaaaaccccccccaacccccccccccccccccccccccccccccaaaaaccccccccaaahhhhppppppppppoooooooofffaaaaccccc
+abaaaaccccccccccaacccccccccccccccccaaacccccccaaaaacccccccccccchhhhhhhhhhggpoooooooffffaaaaccccc
+abccaacccccccacaaaccccccccccccccccaaaaacccccccccccccccccccccccchhhhhhhhhggggoooooffffaacaaacccc
+abccccccccccaaaaacaaccccccccccccccaaaaaccccccccccccccccccccccccchhhhhhhhggggggggggffcaacccccccc
+abccccccccccaaaaaaaaccccccccccccccaaaacccaacccccccccccaccccccccccccccaaaaaggggggggfcccccccccccc
+abccccccccccccaaaaaccccaacccccccccaaaacaaaaccccccccaaaaccccccccccccccaaaacaaagggggcccccccccaccc
+abcccccccccccaaaaacccccaacccccccccaaaaaaaaaccccccccaaaaaaccccccccccccaaaccaaaacccccccccccccaaac
+abcccccccccccaacaaccaaaaaaaacccaaaaaaaaaaaccccccccccaaaaccccccccccccccaccccaaacccccccccccccaaaa
+abccccccccccccccaaccaaaaaaaaccaaaaaaaaaaaccccccccccaaaaacccccccccccccccccccccacccccccccccccaaaa
+abccccccccccccccccccccaaaaacccaaaaaaaaaaaacccccccccaacaacccccccccccccccccccccccccccccccccaaaaaa

2022/rust/src/main.rs

@@ -3,5 +3,5 @@ mod solutions;
 
 
 fn main() {
-    solutions::day11::run();
+    solutions::day12::run();
 }

2022/rust/src/solutions/day12.rs

@@ -0,0 +1,143 @@
+use std::cmp::Ordering;
+use std::collections::{BinaryHeap, HashMap};
+use crate::utils;
+use crate::utils::matrix::Matrix;
+
+
+pub fn run() -> () {
+    let data = parse_data(&utils::read_lines(utils::Source::Day(12)));
+
+    println!("Day 12");
+    println!("Part 1: {}", solve1(&data));
+    println!("Part 2: {}", solve2(&data));
+}
+
+
+type Data = ((usize, usize), (usize, usize), Matrix<u8>);
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+struct State {
+    cost: i32,
+    position: (usize, usize),
+}
+
+impl Ord for State {
+    fn cmp(&self, other: &Self) -> Ordering {
+        other.cost.cmp(&self.cost)
+            .then_with(|| self.position.cmp(&other.position))
+    }
+}
+
+impl PartialOrd for State {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+fn neighbours((row, col): (usize, usize), (rows, cols): (usize, usize)) -> Vec<(usize, usize)> {
+    let mut ns = Vec::with_capacity(4);
+    if row + 1 < rows { ns.push((row + 1, col)) };
+    if 0 < row { ns.push((row - 1, col)) };
+    if col + 1 < cols{ ns.push((row, col + 1)) };
+    if 0 < col { ns.push((row, col - 1)) };
+    ns
+}
+
+fn manhattan(start: (usize, usize), goal: (usize, usize)) -> i32 {
+    (start.0.abs_diff(goal.0) + start.1.abs_diff(goal.1)) as i32
+}
+
+fn unwind_path(
+    parent_map: &HashMap<(usize, usize), (usize, usize)>,
+    start: (usize, usize),
+    goal: (usize, usize),
+) -> Option<Vec<(usize, usize)>> {
+    let mut path = vec![goal];
+    while !path.last()?.eq(&start) {
+        path.push(*parent_map.get(path.last()?)?);
+    }
+    Some(path)
+}
+
+fn a_star(start: (usize, usize), goal: (usize, usize), grid: &Matrix<u8>) -> Vec<(usize, usize)> {
+    let mut frontier: BinaryHeap<State> = BinaryHeap::new();
+    let mut parent: HashMap<(usize, usize), (usize, usize)> = HashMap::new();
+    let mut cost: HashMap<(usize, usize), i32> = HashMap::from([(start, 0)]);
+
+    frontier.push(State { cost: 0, position: start });
+    while let Some(State { position: current, .. }) = frontier.pop() {
+        if current == goal { break };
+
+        for neighbour in neighbours(current, grid.shape()) {
+            // unreachable
+            let level_diff = grid[neighbour].abs_diff(grid[current]);
+            if grid[neighbour] > grid[current] && level_diff > 1 { continue };
+
+            let new_cost = cost.get(&current).unwrap() + 1;
+            if !cost.contains_key(&neighbour) || new_cost < *cost.get(&neighbour).unwrap() {
+                cost.insert(neighbour, new_cost);
+                parent.insert(neighbour, current);
+                frontier.push(State {
+                    cost: new_cost + manhattan(neighbour, goal),
+                    position: neighbour,
+                });
+            }
+        }
+    }
+
+    unwind_path(&parent, start, goal).unwrap()
+}
+
+fn solve1((start, goal, grid): &Data) -> usize {
+    a_star(*start, *goal, grid).len() - 1
+}
+
+fn solve2(data: &Data) -> i32 {
+    2
+}
+
+
+fn parse_data<T: AsRef<str>>(data: &[T]) -> Data {
+    const OFFSET: u8 = 'a' as u8;
+    let mut s = (0, 0);
+    let mut e = (0, 0);
+    let map = data.iter()
+        .enumerate()
+        .flat_map(|(row, line)| {
+            let line = line.as_ref();
+            line.find("S").and_then(|col| Some(s = (row, col)));
+            line.find("E").and_then(|col| Some(e = (row, col)));
+            line.chars().map(|char| match char {
+                'S' => 'a' as u8 - OFFSET,
+                'E' => 'z' as u8 - OFFSET,
+                c => c as u8 - OFFSET
+            })
+        })
+        .collect::<Matrix<_>>()
+        .reshape_rows(data.len());
+    (s, e, map)
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static DATA: &[&str] = &[
+        "Sabqponm",
+        "abcryxxl",
+        "accszExk",
+        "acctuvwj",
+        "abdefghi",
+    ];
+
+    #[test]
+    fn part1() {
+        assert_eq!(31, solve1(&parse_data(DATA)));
+    }
+
+    #[test]
+    fn part2() {
+        assert_eq!(2, solve2(&parse_data(DATA)));
+    }
+}

2022/rust/src/solutions/mod.rs

@@ -9,3 +9,4 @@ pub mod day08;
 pub mod day09;
 pub mod day10;
 pub mod day11;
+pub mod day12;

2022/rust/src/utils/matrix.rs

@@ -1,4 +1,5 @@
 #![allow(dead_code)]
+use std::fmt;
 use std::ops::{Index, IndexMut};
 use std::slice::{ChunksExact, Iter};
 
@@ -111,3 +112,16 @@ impl<T> FromIterator<T> for Matrix<T> {
         Matrix { array, cols, rows: 1 }
     }
 }
+
+impl<T> fmt::Display for Matrix<T> where T: fmt::Display {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for row in self.iter_rows() {
+            for item in row {
+                write!(f, "{}", item)?
+            };
+            write!(f, "\n")?;
+        };
+        Ok(())
+    }
+}
+