perf experiments

2023/16/src/main.rs

@@ -1,7 +1,8 @@
-use std::{fs::File, io::{BufReader, BufRead, Write}, ops::Add, fmt::Debug};
+use std::{fs::File, io::{BufReader, BufRead, Write}, ops::Add, fmt::Debug, collections::HashSet, hash::{Hasher, BuildHasherDefault}};
 
 fn main() {
     part1();
+    part2();
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -46,6 +47,42 @@ struct Beam {
     vector: Vector
 }
 
+impl Beam {
+    fn to_u64(&self) -> u64 {
+        (self.point.x * 100 + self.point.y) * (1 + self.vector.x + 2 * (self.vector.y + 1))
+    }
+}
+
+#[derive(Debug, Default)]
+struct BeamHasher {
+    nums: u64
+}
+
+impl Hasher for BeamHasher {
+    fn write(&mut self, bytes: &[u8]) {
+        // assign bytes directly to nums - this hasher will always get 4 u8s, just once
+        // self.nums = 0;
+        for i in 0..4 {
+            self.nums ^= (bytes[i] as u64) << (i * 8);
+        }
+    }
+
+    fn finish(&self) -> u64 {
+        self.nums
+    }
+}
+
+impl std::hash::Hash for Beam {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        state.write(&[
+            self.point.x as u8,
+            self.point.y as u8,
+            self.vector.x as u8,
+            self.vector.y as u8
+        ]);
+    }
+}
+
 impl Vector {
     fn map_by_mirror(&self, mirror: Type) -> Vector {
         match mirror {
@@ -127,11 +164,11 @@ fn print_energized(energized: &Vec<Vec<bool>>) -> Result<(), std::io::Error> {
     Ok(())
 }
 
-fn append_if_not_in<T: PartialEq + Debug>(vec: &mut Vec<T>, item: T) {
-    if !vec.contains(&item) {
-        vec.push(item);
-    }
-}
+// fn append_if_not_in<T: PartialEq + Debug>(vec: &mut Vec<T>, item: T) {
+//     if !vec.contains(&item) {
+//         vec.push(item);
+//     }
+// }
 fn set_range<T: Copy>(vec: &mut Vec<T>, range: std::ops::Range<usize>, item: T) {
     for i in range {
         vec[i] = item;
@@ -159,14 +196,14 @@ fn mark(vec: Vector, point: Point, otherpos: usize, energized: &mut Vec<Vec<bool
     }
 }
 
-fn part1() {
+fn get_map() -> Vec<Vec<char>> {
     let file = File::open("input2").expect("File not found");
     let reader = BufReader::new(file);
     let map : Vec<Vec<char>> = reader.lines().map(|l| l.unwrap().chars().collect()).collect();
-    let mut energized : Vec<Vec<bool>> = map.iter().map(|l| l.iter().map(|_| false).collect()).collect();
-
-    let max_point = Point { x: map[0].len(), y: map.len() };
+    map
+}
 
+fn get_rows_and_cols(map: Vec<Vec<char>>) -> (Vec<Vec<MapPoint>>, Vec<Vec<MapPoint>>) {
     let rows: Vec<Vec<MapPoint>> = map.iter().enumerate().map(|(y, row)| {
         row
             .iter()
@@ -202,10 +239,23 @@ fn part1() {
             }).collect()
     }).collect();
 
-    let mut beams : Vec<Beam> = vec![Beam {
-        point: Point { x: 0, y: 0 },
-        vector: VEC_RIGHT
-    }];
+    (rows, columns)
+}
+
+fn setup() -> (Point, Vec<Vec<MapPoint>>, Vec<Vec<MapPoint>>) {
+    let map = get_map();
+    // let energized : Vec<Vec<bool>> = map.iter().map(|l| l.iter().map(|_| false).collect()).collect();
+    let max_point = Point { x: map[0].len(), y: map.len() };
+    let (rows, columns) = get_rows_and_cols(map);
+
+    (max_point, rows, columns)
+}
+
+fn get_count(max_point: Point, rows: Vec<Vec<MapPoint>>, columns: Vec<Vec<MapPoint>>, beam: Beam) -> usize {
+    let mut energized : Vec<Vec<bool>> = vec![vec![false; max_point.x]; max_point.y];
+    let mut beams_set = HashSet::<Beam, BuildHasherDefault<BeamHasher>>::default();
+    let mut beams : Vec<Beam> = vec![beam];
+    beams_set.insert(beams[0]);
 
     let mut offset = 0;
 
@@ -214,15 +264,16 @@ fn part1() {
         offset += 1;
 
         let vec = beam.vector;
+        let vec_is_vertical = vec.is_vertical();
         let mut relevant = {
-            (if vec.is_vertical() {
+            (if vec_is_vertical {
                 columns[beam.point.x].iter()
             } else {
                 rows[beam.point.y].iter()
             })
             .filter(|mp| {
-                let mpp = if vec.is_vertical() { mp.point.y } else { mp.point.x };
-                let beamp = if vec.is_vertical() { beam.point.y } else { beam.point.x };
+                let mpp = if vec_is_vertical { mp.point.y } else { mp.point.x };
+                let beamp = if vec_is_vertical { beam.point.y } else { beam.point.x };
                 // ignore splits that are the same direction as the beam
                 mp.mirror != vec.map_to_split() &&
                 (mpp >= beamp && vec.is_positive() || mpp <= beamp && vec.is_negative())
@@ -238,7 +289,7 @@ fn part1() {
                 mark(vec, beam.point, if vec.is_positive() { max_point.x } else { 0 }, &mut energized);
             },
             Some(mappoint) => {
-                mark(vec, beam.point, (if vec.is_vertical() { mappoint.point.y } else { mappoint.point.x } ) + (if vec.is_positive() { 1 } else { 0 }), &mut energized);
+                mark(vec, beam.point, (if vec_is_vertical { mappoint.point.y } else { mappoint.point.x } ) + (if vec.is_positive() { 1 } else { 0 }), &mut energized);
                 let mut vecs = vec![];
                 if mappoint.mirror == Type::SplitHorizontal || mappoint.mirror == Type::SplitVertical {
                     let (v1, v2) = vectors_from_split(mappoint.mirror);
@@ -255,14 +306,62 @@ fn part1() {
                             point: new_point,
                             vector: v
                         };
-                        append_if_not_in(&mut beams, beam);
+                        // append_if_not_in(&mut beams, beam);
+                        if beams_set.insert(beam) {
+                            beams.push(beam);
+                        }
                     }
                 }
             }
         }
     }
-    print_energized(&energized).unwrap();
+    // print_energized(&energized).unwrap();
 
     let count = energized.iter().map(|row| row.iter().filter(|&&b| b).count()).sum::<usize>();
-    println!("Count: {}", count);
+    count
+}
+
+fn part1() {
+    let (max_point, rows, columns) = setup();
+    let count = get_count(max_point, rows, columns, Beam {
+        point: Point { x: 0, y: 0 },
+        vector: VEC_RIGHT
+    });
+    println!("Part 1 count: {}", count);
+}
+
+fn part2() {
+    let (max_point, rows, columns) = setup();
+    let mut count = 0;
+    for x in 0..max_point.x {
+        for y in 0..max_point.y {
+            if x != 0 && y != 0 && x != max_point.x - 1 && y != max_point.y - 1 {
+                continue;
+            }
+            let mut vecs = vec![];
+            if x > 0 {
+                vecs.push(VEC_LEFT);
+            }
+            if x == 0 {
+                vecs.push(VEC_RIGHT);
+            }
+            if y > 0 {
+                vecs.push(VEC_UP);
+            }
+            if y == 0 {
+                vecs.push(VEC_DOWN);
+            }
+            for vector in vecs {
+                let count_here = get_count(max_point, rows.clone(), columns.clone(), Beam {
+                    point: Point { x, y },
+                    vector
+                });
+                if count_here > count {
+                    count = count_here;
+                    println!("New max: {} at {},{}", count, x, y);
+                }
+            }
+        }
+    }
+    println!("Max count: {}", count);
 }