From 0b21e94cf7a84bf9b02a27b8eee8a8a5206e680c Mon Sep 17 00:00:00 2001
From: Justin Wernick <justin@worthe-it.co.za>
Date: Sun, 17 Dec 2023 09:12:54 +0200
Subject: Start of day 17, playing with nalgebra

---
 2023/src/bin/day_17.rs | 63 ++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 56 insertions(+), 7 deletions(-)

(limited to '2023/src/bin')

diff --git a/2023/src/bin/day_17.rs b/2023/src/bin/day_17.rs
index b3a610b..9cd6d76 100644
--- a/2023/src/bin/day_17.rs
+++ b/2023/src/bin/day_17.rs
@@ -1,19 +1,68 @@
-use nom::IResult;
+use nalgebra::{DMatrix, Point2, Unit, Vector2};
+use nom::{
+    character::complete::{line_ending, satisfy},
+    combinator::{map, map_res},
+    multi::{many1, separated_list1},
+    IResult,
+};
 use std::fs;
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let input = fs::read_to_string("inputs/day_2.txt")?;
-    let parsed = Example::parser(&input).unwrap().1;
-    dbg!(&parsed);
+    let input = fs::read_to_string("inputs/day_17.txt")?;
+    let parsed = HeatlossMap::parser(&input).unwrap().1;
+    dbg!(&parsed.find_shortest_heatloss_path());
 
     Ok(())
 }
 
 #[derive(Debug)]
-struct Example;
+struct HeatlossMap(DMatrix<u32>);
+
+#[derive(Debug)]
+struct Position {
+    pos: Point2<usize>,
+    facing: Unit<Vector2<usize>>,
+    duration_with_facing: usize,
+}
+
+impl HeatlossMap {
+    fn parser(input: &str) -> IResult<&str, Self> {
+        map(
+            separated_list1(
+                line_ending,
+                many1(map_res(satisfy(|c| c.is_digit(10)), |d| {
+                    d.to_string().parse::<u32>()
+                })),
+            ),
+            |digits_vec| {
+                HeatlossMap(DMatrix::from_iterator(
+                    digits_vec.len(),
+                    digits_vec[0].len(),
+                    digits_vec.into_iter().flat_map(|row| row.into_iter()),
+                ))
+            },
+        )(input)
+    }
+
+    fn find_shortest_heatloss_path(&self) -> usize {
+        let start = Position {
+            pos: Point2::new(0, 0),
+            facing: Vector2::x_axis(),
+            duration_with_facing: 0,
+        };
+
+        dbg!(&start);
+        dbg!(self.0.get((start.pos.x, start.pos.y)));
+
+        let moved_pos = start.pos + *start.facing;
+        dbg!(&moved_pos);
+        dbg!(self.0.get((moved_pos.x, moved_pos.y)));
+        // start is 0,0
+        // end is max,max
+        // can't go more than 3 in a straight line
+        // can only turn left or right, not go backwards
+        //
 
-impl Example {
-    fn parser(_input: &str) -> IResult<&str, Self> {
         todo!()
     }
 }
-- 
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