day 16: using with_capacity to icrease performance

livexia · livexia · commit 5c6aec68747a · 2023-12-16T15:43:54.000+08:00
diff --git a/aoc16/src/main.rs b/aoc16/src/main.rs
@@ -95,9 +95,9 @@ fn bfs(start_pos: Coord, dir: Direction, grid: &Grid) -> usize {
         queue.push_back((start_pos, d));
     }
 
-    let mut visited = HashSet::new();
+    let mut visited = HashSet::with_capacity(20_000);
 
-    let mut energized = HashSet::new();
+    let mut energized = HashSet::with_capacity(10_000);
 
     while let Some((pos, dir)) = queue.pop_front() {
         energized.insert(pos);

Original file line number	Diff line number	Diff line change
`@@ -95,9 +95,9 @@ fn bfs(start_pos: Coord, dir: Direction, grid: &Grid) -> usize {`
`95`	`95`	`queue.push_back((start_pos, d));`
`96`	`96`	`}`
`97`	`97`
`98`		`- let mut visited = HashSet::new();`
	`98`	`+ let mut visited = HashSet::with_capacity(20_000);`
`99`	`99`
`100`		`- let mut energized = HashSet::new();`
	`100`	`+ let mut energized = HashSet::with_capacity(10_000);`
`101`	`101`
`102`	`102`	`while let Some((pos, dir)) = queue.pop_front() {`
`103`	`103`	`energized.insert(pos);`