Solved day 10

input/day10.txt

@@ -0,0 +1,52 @@
+5678543238765121087216787432128921016563210454323433
+4169654119654037892107894549017430457654782369412812
+3018767001843246543210787678186543368945691078908903
+2189678914980158934345698187098901275632100165001894
+3434589125678767891016521096167872984789321874112765
+7823678034569876780123434545252766543215476903233456
+6910167012423495679654321032341057630306985012945101
+5401986543410584508765678211352348921437894123876298
+4323877892543673210104569300235496530890123434565387
+3210967871652598789213075410145687432765210123432456
+0101454960701659654322186703456710101854321076501201
+1012343459898741023763099812769823478923212987655652
+4323012321101232212854210129876012569012503234234743
+5011001410765540101940110238787112876503414105109892
+6722340543894691001233221045698108976434565696589321
+9821059652023782317874536789587012885325676787678780
+9778968701110678498965945893496543494018989801210690
+8769878889231589567767893672109824323561234892309541
+1454399998342490430850104589678012012370348763458032
+0141287107654321521943213212565503123987659654567123
+1230236256565410101237870101419654598543210508948910
+2340145348978321253210965432308765687696501417654323
+3986501567899010344789876323219454766787432321078890
+5677432450987432455670189410012349845696501434569701
+0548901321976501964563208231987210036723109621435652
+1239678100823457877854010145676210129814918730898543
+4310369234710165756905423210122305610905825623567678
+3423456765600874543814554761201456723876734514410569
+2102109894321984562323669854398556894985232305320438
+3076521003965433871234778034567647895894101476761023
+4585412312870122930129872129867634456783230585872310
+5694303456781211123123401256798521065656187694965432
+6783201019892100054076540346543438980521090123456501
+0340112387653456963981639457832523671439876101219602
+1258903490144327870190128768901214512112725614308712
+2569876589231016983278787434980108903003014525456893
+1876767676546781074349896523076587654394523496327854
+0945778789035690165234765014123496543487621087018969
+1239869876124789234105676543287017012567634589829678
+9018756765453210785411085010196528921298565676543549
+8723605034301305696532398923483437430143476589762138
+7634514125212154387783437654589016521052187679854023
+6501323896521093210598568943078723632367098512763210
+7432454787436789765677678732189654045458963403892001
+8901343474345658894389589823476902102167872354301123
+7623676543216743001210438214567813458054961065689054
+5012389012109812123309321301054324569123452876548765
+4589438729001901014578010102344567078212556989231076
+3676567438782342145665430230133898167901665476102989
+2109652145699654398765421321212101237810174345603478
+1078743034328765219876323478903894376521089298714565
+2167634145410898701101210569816765489432100107623434

input/day10_example.txt

@@ -0,0 +1,8 @@
+89010123
+78121874
+87430965
+96549874
+45678903
+32019012
+01329801
+10456732

src/day10.rs

@@ -0,0 +1,108 @@
+use crate::day_solver::DaySolver;
+#[cfg(test)]
+use crate::util::read_file;
+use crate::util::{Coord, Grid};
+use itertools::Itertools;
+use std::collections::HashSet;
+
+pub struct Day10 {
+    map: Grid<u8>
+}
+
+impl Day10 {
+
+    pub fn create(input: String) -> Self {
+        Day10 {
+            map: Grid {
+                data: input.lines().join("").chars().map(|c| (c as u8) - b'0').collect(),
+                width: input.lines().next().unwrap().len(),
+                default: Some(255)
+            }
+        }
+    }
+
+    fn calculate_score(&self, trailhead: Coord<usize>) -> usize {
+        // Since paths have an even, gradual, uphill slope, we can just go up in height and see what we can reach
+        let mut last_layer: HashSet<Coord<usize>> = HashSet::new();
+        last_layer.insert(trailhead);
+
+        for h in 1..10 {
+            let mut cur_layer = HashSet::new();
+            for pos in last_layer.clone() {
+                // Check which neighbors are height h
+                if self.map.get(pos.x + 1, pos.y) == &h { cur_layer.insert(Coord::new(pos.x + 1, pos.y)); };
+                if pos.x > 0 && self.map.get(pos.x - 1, pos.y) == &h { cur_layer.insert(Coord::new(pos.x - 1, pos.y)); };
+                if self.map.get(pos.x, pos.y + 1) == &h { cur_layer.insert(Coord::new(pos.x, pos.y + 1)); };
+                if pos.y > 0 && self.map.get(pos.x, pos.y - 1) == &h { cur_layer.insert(Coord::new(pos.x, pos.y - 1)); };
+            }
+            last_layer = cur_layer;
+        }
+
+        last_layer.len()
+    }
+
+    fn update_pos(&self, new_x: usize, new_y: usize, target_height: &u8, cur_paths_to_pos: usize, cur_layer: &mut HashSet<Coord<usize>>, paths_to_pos: &mut Grid<usize>) {
+
+        if self.map.get(new_x, new_y) == target_height {
+            cur_layer.insert(Coord::new(new_x, new_y));
+            paths_to_pos.set(new_x, new_y, paths_to_pos.get(new_x, new_y) + cur_paths_to_pos);
+        }
+    }
+
+    fn calculate_score_pt2(&self, trailhead: Coord<usize>) -> usize {
+        
+        let mut last_layer: HashSet<Coord<usize>> = HashSet::new();
+        last_layer.insert(trailhead);
+
+        let mut paths_to_pos: Grid<usize> = Grid {
+                data: vec![0; self.map.data.len()],
+                width: self.map.width,
+                default: Some(0),
+        };
+        paths_to_pos.set(trailhead.x, trailhead.y, 1);
+
+        for h in 1..10 {
+            let mut cur_layer = HashSet::new();
+            for pos in last_layer.clone() {
+                let cur_paths_to_pos = paths_to_pos.get(pos.x, pos.y).to_owned();
+                self.update_pos(pos.x + 1, pos.y, &h, cur_paths_to_pos, &mut cur_layer, &mut paths_to_pos);
+                if pos.x > 0 { self.update_pos(pos.x - 1, pos.y, &h, cur_paths_to_pos, &mut cur_layer, &mut paths_to_pos); };
+                self.update_pos(pos.x, pos.y + 1, &h, cur_paths_to_pos, &mut cur_layer, &mut paths_to_pos);
+                if pos.y > 0 { self.update_pos(pos.x, pos.y - 1, &h, cur_paths_to_pos, &mut cur_layer, &mut paths_to_pos); };
+
+            }
+            last_layer = cur_layer;
+        }
+
+        last_layer.iter().map(|l| paths_to_pos.get(l.x, l.y)).sum()
+    }
+}
+
+impl DaySolver for Day10 {
+
+
+    fn solve_part1(&mut self) -> String {
+        self.map.find_positions(&|d| d == &0)
+            .map(|c| self.calculate_score(c))
+            .sum::<usize>().to_string()
+
+    }
+
+    fn solve_part2(&mut self) -> String {
+        self.map.find_positions(&|d| d == &0)
+            .map(|c| self.calculate_score_pt2(c))
+            .sum::<usize>().to_string()
+    }
+}
+
+#[test]
+fn test_part1() {
+    let mut day = Day10::create(read_file("input/day10_example.txt"));
+    assert_eq!("36", day.solve_part1());
+}
+
+#[test]
+fn test_part2() {
+    let mut day = Day10::create(read_file("input/day10_example.txt"));
+    assert_eq!("81", day.solve_part2());
+}

src/main.rs

@@ -1,6 +1,7 @@
 extern crate core;
 
 use std::time::Instant;
+use crate::day10::Day10;
 use crate::day1::Day1;
 use crate::day2::Day2;
 use crate::day3::Day3;
@@ -24,6 +25,7 @@ mod day6;
 mod day7;
 mod day8;
 mod day9;
+mod day10;
 
 const DEFAULT_BENCHMARK_AMOUNT: u32 = 100;
 
@@ -104,7 +106,7 @@ fn build_day_solver(day: u8, input: String) -> Option<Box<dyn DaySolver>> {
         7 => Some(Box::new(Day7::create(input))),
         8 => Some(Box::new(Day8::create(input))),
         9 => Some(Box::new(Day9::create(input))),
-        // 10 => Some(Box::new(Day10::create(input))),
+        10 => Some(Box::new(Day10::create(input))),
         // 11 => Some(Box::new(Day11::create(input))),
         // 12 => Some(Box::new(Day12::create(input))),
         _ => None