Day 18 part 1

2 files changed, 781 insertions, 9 deletions

diff --git a/2023/inputs/day_18.txt b/2023/inputs/day_18.txt
new file mode 100644
index 0000000..785855d
--- /dev/null
+++ b/2023/inputs/day_18.txt
@@ -0,0 +1,604 @@
+L 9 (#2ee530)
+U 6 (#14ffa3)
+L 10 (#6b5400)
+U 8 (#14ffa1)
+L 3 (#01d650)
+U 8 (#37eb83)
+L 7 (#9c0f82)
+U 5 (#406fa3)
+L 10 (#1f7e90)
+U 3 (#074881)
+R 4 (#5ee970)
+U 8 (#27d063)
+R 4 (#89e940)
+U 6 (#27d061)
+R 4 (#6780e0)
+D 7 (#074883)
+R 3 (#3318a0)
+D 7 (#4699f3)
+R 5 (#450d72)
+U 9 (#44b753)
+R 9 (#450d70)
+U 3 (#2944f3)
+R 10 (#4cb000)
+U 8 (#237e11)
+L 7 (#0f7ff0)
+U 7 (#7bafc1)
+L 2 (#0f7ff2)
+D 7 (#156861)
+L 7 (#426ee0)
+U 4 (#6ab653)
+L 3 (#688b20)
+U 5 (#7988c3)
+L 7 (#4884c2)
+D 5 (#572ed3)
+L 4 (#666412)
+D 4 (#572ed1)
+L 4 (#48c282)
+U 12 (#7565e3)
+R 3 (#2ed560)
+U 3 (#11bfd3)
+R 7 (#7aa950)
+U 9 (#11bfd1)
+R 4 (#4e2ca0)
+D 12 (#0e4b53)
+R 6 (#652dd0)
+U 12 (#049ee3)
+R 8 (#238522)
+D 12 (#343033)
+R 6 (#5e6622)
+U 12 (#343031)
+L 3 (#4bcdb2)
+U 3 (#421173)
+L 6 (#6f8cd0)
+U 2 (#08a353)
+L 9 (#827572)
+U 5 (#14a293)
+L 4 (#46d982)
+U 6 (#14a291)
+L 9 (#52bec2)
+U 3 (#38e5c1)
+L 9 (#188ae2)
+U 9 (#4d0573)
+R 6 (#5b2b12)
+U 3 (#4d0571)
+R 6 (#409982)
+U 9 (#38e5c3)
+R 10 (#31b872)
+U 3 (#1e0b33)
+L 3 (#5e2382)
+U 7 (#1e0b31)
+L 12 (#415d62)
+U 6 (#2e1a53)
+L 5 (#935920)
+D 11 (#5b0873)
+L 3 (#10b382)
+U 11 (#29fee1)
+L 5 (#69aa92)
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+L 10 (#0766f0)
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+R 7 (#5baef0)
+D 2 (#31c1b3)
+R 6 (#5aeba0)
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+R 5 (#268450)
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+D 3 (#355353)
+R 5 (#388240)
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+L 8 (#705030)
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+R 8 (#705032)
+U 3 (#095781)
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+R 6 (#25be80)
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+R 8 (#0c04c0)
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+R 8 (#8dadb0)
+U 4 (#3e4341)
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+R 8 (#2670e0)
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+R 3 (#0c5eb0)
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+D 3 (#430261)
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+D 4 (#609ca1)
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+U 4 (#03f783)
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+D 8 (#1f9381)
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+R 5 (#057992)
+D 5 (#312681)
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+R 3 (#60a5d2)
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+R 9 (#132772)
+D 5 (#146901)
+R 8 (#12b2b2)
+U 5 (#146903)
+R 4 (#32ea72)
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+U 3 (#4783a1)
+L 12 (#4f7110)
+U 6 (#2ee201)
+R 10 (#56c732)
+U 6 (#2eb4c1)
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+D 11 (#64c0b3)
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+L 9 (#34d010)
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+U 6 (#192461)
+R 4 (#353062)
+U 6 (#7fa931)
+R 9 (#353060)
+D 6 (#36c4e1)
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+R 7 (#025440)
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+R 10 (#3b9e20)
+U 9 (#42d061)
+R 7 (#64f852)
+U 10 (#656b91)
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+R 2 (#49bf20)
+U 7 (#30c543)
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+U 4 (#690161)
+L 5 (#232940)
+U 5 (#3c9dc1)
+L 8 (#71a6b0)
+D 10 (#5d7671)
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+U 10 (#4d49b1)
+L 6 (#213662)
+D 5 (#263fa1)
+L 7 (#86c7e2)
+D 7 (#644a91)
+L 6 (#16b772)
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+L 5 (#1e0682)
+U 4 (#77d461)
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+R 3 (#197b02)
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+L 6 (#2741d0)
+D 5 (#5e6823)
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+L 5 (#42be90)
+U 7 (#5c3273)
+R 6 (#389cd0)
+U 5 (#527673)
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+U 8 (#6737e3)
+R 3 (#49ffc0)
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+R 5 (#3aeb12)
+D 7 (#5afeb1)
+R 4 (#647082)
+D 7 (#5aa271)
+R 2 (#647080)
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+R 8 (#3aeb10)
+D 6 (#272d01)
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+U 4 (#767071)
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+L 7 (#1a0942)
+U 6 (#38ca33)
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+U 3 (#21adf3)
+R 2 (#6c2ff2)
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+U 8 (#2d5193)
+R 8 (#2a9172)
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+R 4 (#57de32)
+D 4 (#2e23a1)
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+R 4 (#614872)
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+D 13 (#1ef063)
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+D 12 (#2e3061)
+L 10 (#4df090)
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+D 10 (#2c3851)
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+D 6 (#2c3853)
+L 7 (#00bbc0)
+D 4 (#1ef061)
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+D 5 (#48a201)
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+D 5 (#0dbdd1)
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+D 8 (#6f86a1)
+L 5 (#0b6fb0)
+D 2 (#409341)
+R 5 (#6c37f0)
+D 7 (#0168f3)
+L 5 (#3f7660)
+D 5 (#417793)
+L 2 (#57f4f2)
+D 6 (#0bd113)
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+D 2 (#4dc503)
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+D 3 (#1742c1)
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+R 2 (#746850)
+D 6 (#2d7331)
+R 13 (#728a50)
+D 9 (#2d7333)
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+D 3 (#5a55c1)
+R 7 (#8135d0)
+D 4 (#3a5821)
+R 9 (#0e2950)
+D 8 (#3a69b1)
+R 2 (#44c4c2)
+U 8 (#49c381)
+R 9 (#44c4c0)
+D 7 (#3ec4a1)
+R 7 (#1d6772)
+U 3 (#2ebbb1)
+R 5 (#0dde42)
+U 8 (#305d51)
+R 9 (#542a62)
+U 10 (#56fc71)
+L 9 (#1e1572)
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+U 5 (#2d9c31)
+R 8 (#173092)
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+R 8 (#03d872)
+D 10 (#3eed33)
+L 8 (#03d870)
+D 7 (#44f2c3)
+R 5 (#504132)
+D 9 (#44e7f3)
+R 5 (#814902)
+D 3 (#027683)
+R 8 (#566fe2)
+U 9 (#060e01)
+R 12 (#49b352)
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+U 5 (#6b39e1)
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+L 4 (#49bbe2)
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+R 7 (#756482)
+U 11 (#2738a1)
+R 4 (#2988e2)
+D 11 (#02fca1)
+R 6 (#192a82)
+U 6 (#67dba1)
+R 10 (#75f442)
+D 6 (#2b3a51)
+R 5 (#117142)
+U 13 (#248943)
+R 6 (#91c3d2)
+D 13 (#248941)
+R 3 (#00b892)
+D 5 (#12f861)
+L 3 (#0620d2)
+D 5 (#4ef3b1)
+L 5 (#2498c2)
+U 5 (#385601)
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+D 9 (#36f331)
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+U 4 (#257851)
+R 2 (#04b552)
+U 6 (#4c0321)
+L 8 (#258f72)
+U 6 (#247543)
+R 8 (#3da442)
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+D 6 (#1e95f3)
+R 9 (#6332e2)
+D 7 (#5f7223)
+L 5 (#053e92)
+D 7 (#208543)
+L 6 (#1e3f82)
+U 7 (#0368c3)
+L 5 (#6fa270)
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+D 5 (#38ad13)
+R 4 (#0d8a72)
+D 8 (#46d1c3)
+L 4 (#3da9f0)
+D 6 (#42a123)
+L 4 (#2b46c0)
+U 11 (#5fd0d3)
+L 7 (#2d5dd2)
+U 6 (#4b50e3)
+L 3 (#62fb72)
+U 5 (#23cb83)
+L 7 (#1f4562)
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+D 5 (#0f3c53)
+R 10 (#35bed2)
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+D 3 (#6e0603)
+R 5 (#3754a2)
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+D 12 (#4a4993)
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+U 13 (#057dd3)
+L 7 (#881722)
+U 2 (#057dd1)
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+U 3 (#6e8593)
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+U 12 (#434f73)
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+U 12 (#307143)
+L 2 (#2afed0)
+U 9 (#64b4b3)
+L 8 (#81b252)
+U 4 (#3b1b83)
+L 7 (#3bea42)
+U 3 (#002181)
+R 11 (#78d502)
+U 8 (#002183)
+L 11 (#2a9612)
+U 4 (#569aa3)
+L 6 (#39f100)
+D 5 (#85bf33)
+L 4 (#204170)
+D 4 (#85bf31)
+R 4 (#4af060)
+D 6 (#32ee33)
+L 7 (#260090)
+U 7 (#600543)
+L 2 (#5a3890)
+U 11 (#0d8dc3)
+L 6 (#2560e0)
+D 10 (#7a8d43)
+L 8 (#5daed2)
+D 9 (#1ef063)
+L 12 (#31ac32)
+D 4 (#6ba891)
+L 6 (#2cd302)
+U 13 (#6ba893)
+L 6 (#49a4e2)
+D 12 (#1ef061)
+L 9 (#44e9f2)
+D 10 (#58adc3)
+R 3 (#425842)
+D 6 (#0a8503)
+R 13 (#39aa52)
+U 6 (#0a8501)
+R 8 (#371d22)
+D 11 (#0ba1a3)
+L 3 (#5bbaf2)
+D 5 (#7cb2f3)
+L 6 (#2677a2)
+U 6 (#37f2c1)
+L 3 (#900172)
+D 6 (#2b1251)
+L 6 (#245ed2)
+U 5 (#630513)
+L 6 (#1ec542)
+D 7 (#59e363)
+L 6 (#843450)
+U 4 (#406233)
+L 8 (#450400)
+U 6 (#997ff1)
+L 6 (#2fd6d0)
+D 4 (#997ff3)
+L 7 (#2a5340)
+D 6 (#406231)
+L 11 (#31f5b0)
+U 7 (#121183)
+L 4 (#053ae2)
+U 6 (#88cca3)
+R 7 (#053ae0)
+U 6 (#114cd3)
+L 7 (#2d4c62)
+U 9 (#1eff63)
+L 4 (#48d402)
+U 10 (#470983)
diff --git a/2023/src/bin/day_18.rs b/2023/src/bin/day_18.rs
index b3a610b..c3e9f58 100644
--- a/2023/src/bin/day_18.rs
+++ b/2023/src/bin/day_18.rs
@@ -1,19 +1,187 @@
-use nom::IResult;
-use std::fs;
+use nalgebra::{Point2, Vector2};
+use nom::{
+    branch::alt,
+    bytes::complete::{tag, take},
+    character::complete::{char, hex_digit1, line_ending, space1, u32},
+    combinator::{map, map_res, value},
+    multi::separated_list1,
+    sequence::tuple,
+    IResult,
+};
+use std::{collections::HashMap, 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_18.txt")?;
+    let parsed = Instructions::parser(&input).unwrap().1;
+    let mut fill_map = parsed.draw_map();
+    fill_map.derive_inside_outside();
+    dbg!(&fill_map.count_inside());
 
+    let hex_parsed = Instructions::hex_parser(&input).unwrap().1;
+    dbg!(&hex_parsed);
     Ok(())
 }
 
 #[derive(Debug)]
-struct Example;
+struct Instructions(Vec<Instruction>);
 
-impl Example {
-    fn parser(_input: &str) -> IResult<&str, Self> {
-        todo!()
+#[derive(Debug)]
+struct Instruction {
+    direction: Vector2<i32>,
+    distance: u32,
+}
+
+#[derive(Debug)]
+struct FloodFillMap {
+    map: HashMap<Point2<i32>, Fill>,
+    top_left: Point2<i32>,
+    bottom_right: Point2<i32>,
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+enum Fill {
+    Outside,
+    Inside,
+}
+
+impl Instructions {
+    fn parser(input: &str) -> IResult<&str, Self> {
+        map(
+            separated_list1(line_ending, Instruction::parser),
+            Instructions,
+        )(input)
+    }
+
+    fn hex_parser(input: &str) -> IResult<&str, Self> {
+        map(
+            separated_list1(line_ending, Instruction::hex_parser),
+            Instructions,
+        )(input)
+    }
+
+    fn draw_map(&self) -> FloodFillMap {
+        let mut trench = HashMap::new();
+        let mut current = Point2::new(0, 0);
+        for instruction in &self.0 {
+            for _ in 0..instruction.distance {
+                current += instruction.direction;
+                trench.insert(current.clone(), Fill::Inside);
+            }
+        }
+
+        FloodFillMap::new(trench)
+    }
+}
+
+impl Instruction {
+    fn parser(input: &str) -> IResult<&str, Self> {
+        map(
+            tuple((
+                dir_parser,
+                space1,
+                u32,
+                space1,
+                tag("(#"),
+                hex_digit1,
+                tag(")"),
+            )),
+            |(direction, _, distance, _, _, _, _)| Instruction {
+                direction,
+                distance,
+            },
+        )(input)
+    }
+
+    fn hex_parser(input: &str) -> IResult<&str, Self> {
+        map(
+            tuple((
+                dir_parser,
+                space1,
+                u32,
+                space1,
+                tag("(#"),
+                map_res(take(5usize), |hex| u32::from_str_radix(hex, 16)),
+                hex_dir_parser,
+                tag(")"),
+            )),
+            |(_, _, _, _, _, distance, direction, _)| Instruction {
+                direction,
+                distance,
+            },
+        )(input)
+    }
+}
+
+fn dir_parser(input: &str) -> IResult<&str, Vector2<i32>> {
+    alt((
+        value(Vector2::new(0, -1), char('U')),
+        value(Vector2::new(0, 1), char('D')),
+        value(Vector2::new(-1, 0), char('L')),
+        value(Vector2::new(1, 0), char('R')),
+    ))(input)
+}
+
+fn hex_dir_parser(input: &str) -> IResult<&str, Vector2<i32>> {
+    alt((
+        value(Vector2::new(0, -1), char('3')),
+        value(Vector2::new(0, 1), char('1')),
+        value(Vector2::new(-1, 0), char('2')),
+        value(Vector2::new(1, 0), char('0')),
+    ))(input)
+}
+
+impl FloodFillMap {
+    fn new(map: HashMap<Point2<i32>, Fill>) -> FloodFillMap {
+        let top_left = Point2::new(
+            map.keys().map(|key| key.x).min().unwrap() - 1,
+            map.keys().map(|key| key.y).min().unwrap() - 1,
+        );
+
+        let bottom_right = Point2::new(
+            map.keys().map(|key| key.x).max().unwrap() + 1,
+            map.keys().map(|key| key.y).max().unwrap() + 1,
+        );
+
+        FloodFillMap {
+            map,
+            top_left,
+            bottom_right,
+        }
+    }
+
+    fn derive_inside_outside(&mut self) {
+        self.flood_fill(self.top_left.clone(), &Fill::Outside);
+        for y in self.top_left.y..=self.bottom_right.y {
+            for x in self.top_left.x..=self.bottom_right.x {
+                let current = Point2::new(x, y);
+                self.map.entry(current).or_insert(Fill::Inside);
+            }
+        }
+    }
+
+    fn count_inside(&self) -> usize {
+        self.map
+            .values()
+            .filter(|fill| **fill == Fill::Inside)
+            .count()
+    }
+
+    fn flood_fill(&mut self, start: Point2<i32>, fill: &Fill) {
+        let mut to_fill = vec![start];
+
+        while let Some(next) = to_fill.pop() {
+            if next.y >= self.top_left.y
+                && next.x >= self.top_left.x
+                && next.y <= self.bottom_right.y
+                && next.x <= self.bottom_right.x
+                && !self.map.contains_key(&next)
+            {
+                self.map.insert(next.clone(), fill.clone());
+                to_fill.push(next + Vector2::new(-1, 0));
+                to_fill.push(next + Vector2::new(1, 0));
+                to_fill.push(next + Vector2::new(0, -1));
+                to_fill.push(next + Vector2::new(0, 1));
+            }
+        }
     }
 }