From a0653a8223b346215ababacb7eb8f55049977812 Mon Sep 17 00:00:00 2001
From: Rh4096 <rhelvetican@gmail.com>
Date: Tue, 10 Dec 2024 14:00:12 +0700
Subject: [PATCH] day 10

---
 src/main.rs             |   3 +-
 src/solutions/day_10.rs | 124 ++++++++++++++++++++++++++++++++++++++--
 src/utils/coord.rs      |  11 ++++
 3 files changed, 132 insertions(+), 6 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index f7e52eb..3c28fb0 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -30,7 +30,8 @@ fn main() -> Result<()> {
         6 => AocDaySixSolution,
         7 => AocDaySevenSolution,
         8 => AocDayEightSolution,
-        9 => AocDayNineSolution
+        9 => AocDayNineSolution,
+        10 => AocDayTenSolution,
     };
 
     Ok(())
diff --git a/src/solutions/day_10.rs b/src/solutions/day_10.rs
index a78b198..9fa47a1 100644
--- a/src/solutions/day_10.rs
+++ b/src/solutions/day_10.rs
@@ -1,8 +1,120 @@
-use std::{fs::read_to_string, path::Path};
+use std::{
+    collections::{HashMap, HashSet},
+    fs::read_to_string,
+    path::Path,
+};
 
 use super::AocSolution;
-use crate::utils::Result;
+use crate::utils::{coord::Coord as Crd, Result};
 
+type Coord = Crd<i8>;
+
+struct HikingMap {
+    pub starting_points: HashSet<Coord>,
+    pub mountain: HashMap<Coord, u8>,
+}
+
+impl HikingMap {
+    fn new(src: &str) -> Self {
+        let (starting_points, mountain) = src
+            .lines()
+            .zip(0..)
+            .flat_map(|(line, y)| {
+                line.chars().zip(0..).filter_map(move |(ch, x)| match ch {
+                    '0' => Some((Coord::new(x, y), 0)),
+                    '1' => Some((Coord::new(x, y), 1)),
+                    '2' => Some((Coord::new(x, y), 2)),
+                    '3' => Some((Coord::new(x, y), 3)),
+                    '4' => Some((Coord::new(x, y), 4)),
+                    '5' => Some((Coord::new(x, y), 5)),
+                    '6' => Some((Coord::new(x, y), 6)),
+                    '7' => Some((Coord::new(x, y), 7)),
+                    '8' => Some((Coord::new(x, y), 8)),
+                    '9' => Some((Coord::new(x, y), 9)),
+                    _ => None,
+                })
+            })
+            .fold(
+                (HashSet::new(), HashMap::new()),
+                |(mut spos, mut map), (coord, heigh)| {
+                    if heigh == 0 {
+                        spos.insert(coord);
+                    }
+
+                    map.insert(coord, heigh);
+
+                    (spos, map)
+                },
+            );
+
+        Self {
+            starting_points,
+            mountain,
+        }
+    }
+
+    fn hike(&self) -> u64 {
+        fn _inner(map: &HashMap<Coord, u8>, start_pos: Coord) -> u64 {
+            fn _traverse(map: &HashMap<Coord, u8>, summits: &mut HashSet<Coord>, current: Coord) {
+                if map.get(&current).is_some_and(|h| h == &9) {
+                    summits.insert(current);
+                    return;
+                }
+
+                for dir in current.surround() {
+                    if map.get(&dir).is_some_and(|&h| map[&current] + 1 == h) {
+                        _traverse(map, summits, dir);
+                    }
+                }
+            }
+
+            let mut visited = HashSet::new();
+            if map.contains_key(&start_pos) {
+                _traverse(map, &mut visited, start_pos);
+                visited.len() as u64
+            } else {
+                0
+            }
+        }
+
+        self.starting_points
+            .iter()
+            .map(|pos| _inner(&self.mountain, *pos))
+            .sum()
+    }
+
+    fn hike_ver_two(&self) -> u64 {
+        fn _inner(map: &HashMap<Coord, u8>, start_pos: Coord) -> u64 {
+            fn _traverse(map: &HashMap<Crd<i8>, u8>, current: Coord, rate: &mut u64) {
+                if map.get(&current).is_some_and(|h| h == &9) {
+                    *rate += 1;
+                    return;
+                }
+
+                for dir in current.surround() {
+                    if map.get(&dir).is_some_and(|&h| map[&current] + 1 == h) {
+                        _traverse(map, dir, rate);
+                    }
+                }
+            }
+
+            let mut rating = 0;
+            if map.contains_key(&start_pos) {
+                _traverse(map, start_pos, &mut rating);
+                rating
+            } else {
+                0
+            }
+        }
+
+        self.starting_points
+            .iter()
+            .map(|pos| _inner(&self.mountain, *pos))
+            .sum()
+    }
+}
+
+#[derive(Clone, Copy)]
 pub struct AocDayTenSolution;
 
 impl AocSolution for AocDayTenSolution {
@@ -11,15 +123,17 @@ impl AocSolution for AocDayTenSolution {
     fn get_input(&self, path: Option<&Path>) -> Result<String> {
         Ok(match path {
             Some(p) => read_to_string(p)?,
-            None => read_to_string("./input/day_day_10.txt")?,
+            None => read_to_string("./input/day_10.txt")?,
         })
     }
 
     fn part_one(&self, input: &str) -> Result<Self::Output> {
-        todo!()
+        let map = HikingMap::new(input);
+        Ok(map.hike())
     }
 
     fn part_two(&self, input: &str) -> Result<Self::Output> {
-        todo!()
+        let map = HikingMap::new(input);
+        Ok(map.hike_ver_two())
     }
 }
diff --git a/src/utils/coord.rs b/src/utils/coord.rs
index b2c5314..7398788 100644
--- a/src/utils/coord.rs
+++ b/src/utils/coord.rs
@@ -13,9 +13,20 @@ pub struct Coord<U: Unit> {
 }
 
 impl<U: Unit> Coord<U> {
+    #[inline(always)]
     pub const fn new(x: U, y: U) -> Self {
         Self { x, y }
     }
+
+    #[inline(always)]
+    pub fn surround(&self) -> [Self; 4] {
+        [
+            Self::new(self.x - U::from(1), self.y),
+            Self::new(self.x, self.y + U::from(1)),
+            Self::new(self.x + U::from(1), self.y),
+            Self::new(self.x, self.y - U::from(1)),
+        ]
+    }
 }
 
 impl<U: Unit> Add for Coord<U> {