perf: optimize dijkstra all_paths by searching form end to start

manhunto · Dec 23, 2024 · 205d3a1 · 205d3a1
1 parent 2539c2c
commit 205d3a1
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Showing 2 changed files with 5 additions and 9 deletions.
diff --git a/readme.md b/readme.md
@@ -26,7 +26,7 @@
 | [Day 13: Claw Contraption](src/solutions/year2024/day13.rs)       |   ⭐⭐   |            0.241 |            0.331 |
 | [Day 14: Restroom Redoubt](src/solutions/year2024/day14.rs)       |   ⭐⭐   |            0.172 |          102.252 |
 | [Day 15: Warehouse Woes](src/solutions/year2024/day15.rs)         |   ⭐⭐   |            7.226 |            9.084 |
-| [Day 16: Reindeer Maze](src/solutions/year2024/day16.rs)          |   ⭐⭐   |            6.478 |        22716.831 |
+| [Day 16: Reindeer Maze](src/solutions/year2024/day16.rs)          |   ⭐⭐   |            6.478 |           74.105 |
 | [Day 17: Chronospatial Computer](src/solutions/year2024/day17.rs) |   -    |                - |                - |
 | [Day 18: RAM Run](src/solutions/year2024/day18.rs)                |   ⭐⭐   |            2.487 |          204.885 |
 | [Day 19: Linen Layout](src/solutions/year2024/day19.rs)           |   ⭐⭐   |            2.923 |           22.751 |

diff --git a/src/utils/graphs/dijkstra.rs b/src/utils/graphs/dijkstra.rs
@@ -145,22 +145,18 @@ impl<'a, T> Dijkstra<'a, T> {
         T: Hash + Eq + PartialEq + Ord + Debug + Copy,
     {
         {
-            visited.push(from);
-            path.push_back(from);
+            visited.push(end);
+            path.push_front(end);
 
             if from == end {
                 paths.push(path.clone());
 
                 return;
             }
 
-            for p in come_from
-                .iter()
-                .filter(|(_, froms)| froms.contains(&from))
-                .map(|(to, _)| to)
-            {
+            for p in come_from.get(&end).unwrap_or(&Vec::new()) {
                 if !visited.contains(p) {
-                    Self::visit(*p, end, visited.clone(), path.clone(), paths, come_from);
+                    Self::visit(from, *p, visited.clone(), path.clone(), paths, come_from);
                 }
             }
         }