From 5502c35f06c2fb3d92721a55521ad0277a7e669f Mon Sep 17 00:00:00 2001
From: Daniel Bulant <danbulant@gmail.com>
Date: Sun, 17 Dec 2023 12:21:14 +0100
Subject: [PATCH] experiment with less memory

---
 2023/16/src/main.rs | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/2023/16/src/main.rs b/2023/16/src/main.rs
index c2a4585..40244ed 100644
--- a/2023/16/src/main.rs
+++ b/2023/16/src/main.rs
@@ -1,4 +1,4 @@
-use std::{fs::File, io::{BufReader, BufRead, Write}, ops::Add, fmt::Debug, collections::HashSet, hash::{Hasher, BuildHasherDefault}, process::exit};
+use std::{fs::File, io::{BufReader, BufRead, Write}, ops::Add, fmt::Debug, hash::Hasher};
 
 fn main() {
     part1();
@@ -73,10 +73,11 @@ struct Beam {
 // ];
 
 impl Beam {
-    fn to_u64(&self) -> usize {
+    fn to_nums(&self) -> (usize, usize) {
         let vecval = (self.vector.x+1)*self.vector.x.abs()+(self.vector.y+2)*self.vector.y.abs();
         let val = (self.point.x * 110 + self.point.y + 1) << 2 | vecval as usize;
-        val
+        (val >> 6, 1 << (val & 63))
+        // 0b1000000000000000000000000000000000000000000000000000000000000000
     }
 }
 
@@ -281,10 +282,11 @@ fn setup() -> (Point, Vec<Vec<MapPoint>>, Vec<Vec<MapPoint>>) {
 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_set_vec = vec![false; (max_point.x + 1) * (max_point.y + 1) * 4];
+    let mut beams_set_vec = vec![0; (max_point.x + 1) * (max_point.y + 1) / 8 + 1];
     let mut beams : Vec<Beam> = vec![beam];
     // beams_set.insert(beams[0]);
-    beams_set_vec[beams[0].to_u64()] = true;
+    let b0 = beams[0].to_nums();
+    beams_set_vec[b0.0] = b0.1;
 
     let mut offset = 0;
 
@@ -337,9 +339,9 @@ fn get_count(max_point: Point, rows: Vec<Vec<MapPoint>>, columns: Vec<Vec<MapPoi
                         };
                         // append_if_not_in(&mut beams, beam);
                         // if beams_set.insert(beam) {
-                        let bnum = beam.to_u64();
-                        if beams_set_vec[bnum] == false {
-                            beams_set_vec[bnum] = true;
+                        let bnum = beam.to_nums();
+                        if beams_set_vec[bnum.0] & bnum.1 == 0 {
+                            beams_set_vec[bnum.0] |= bnum.1;
                             beams.push(beam);
                         }
                     }