From 9e2e317f8d30405c877d288f7778a6929cfc06ed Mon Sep 17 00:00:00 2001
From: Glenn Griffin <ggriffiniii@gmail.com>
Date: Fri, 18 Dec 2020 16:08:14 -0800
Subject: [PATCH] day17 part2

---
 src/day17.rs | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/src/day17.rs b/src/day17.rs
index ede9bfe..6ad574e 100644
--- a/src/day17.rs
+++ b/src/day17.rs
@@ -8,7 +8,7 @@ fn solve_d17_p1(input: &str) -> usize {
         for (x, _) in line.as_bytes().iter().copied().enumerate().filter(|&(_, byte)| {
             byte == b'#'
         }) {
-            world.insert((x as isize, y as isize, 0isize));
+            world.insert((x as isize, y as isize, 0isize, 0isize));
         }
     }
     for _ in 0 .. 6 {
@@ -17,19 +17,21 @@ fn solve_d17_p1(input: &str) -> usize {
     world.len()
 }
 
-fn neighbors(world: &HashSet<(isize, isize, isize)>, (x, y, z): (isize, isize, isize)) -> usize {
+fn neighbors(world: &HashSet<(isize, isize, isize, isize)>, (x, y, z, w): (isize, isize, isize, isize)) -> usize {
     let mut count = 0;
     for xa in x-1..=x+1 {
         for ya in y-1..=y+1 {
             for za in z-1..=z+1 {
-                count += world.contains(&(xa, ya, za)) as usize;
+                for wa in w-1..=w+1 {
+                    count += world.contains(&(xa, ya, za, wa)) as usize;
+                }
             }
         }
     }
-    count - world.contains(&(x, y, z)) as usize
+    count - world.contains(&(x, y, z, w)) as usize
 }
 
-fn step(world: HashSet<(isize, isize, isize)>) -> HashSet<(isize, isize, isize)> {
+fn step(world: HashSet<(isize, isize, isize, isize)>) -> HashSet<(isize, isize, isize, isize)> {
     struct MinMax {
         x_min: isize,
         x_max: isize,
@@ -37,9 +39,11 @@ fn step(world: HashSet<(isize, isize, isize)>) -> HashSet<(isize, isize, isize)>
         y_max: isize,
         z_min: isize,
         z_max: isize,
+        w_min: isize,
+        w_max: isize,
     }
     let MinMax{
-        x_min, x_max, y_min, y_max, z_min, z_max,
+        x_min, x_max, y_min, y_max, z_min, z_max, w_min, w_max,
     } = world.iter().fold(MinMax{
         x_min: isize::MAX,
         x_max: isize::MIN,
@@ -47,7 +51,9 @@ fn step(world: HashSet<(isize, isize, isize)>) -> HashSet<(isize, isize, isize)>
         y_max: isize::MIN,
         z_min: isize::MAX,
         z_max: isize::MIN,
-    }, |minmax, &(x, y, z)| {
+        w_min: isize::MAX,
+        w_max: isize::MIN,
+    }, |minmax, &(x, y, z, w)| {
         MinMax{
             x_min: std::cmp::min(minmax.x_min, x),
             x_max: std::cmp::max(minmax.x_max, x),
@@ -55,19 +61,23 @@ fn step(world: HashSet<(isize, isize, isize)>) -> HashSet<(isize, isize, isize)>
             y_max: std::cmp::max(minmax.y_max, y),
             z_min: std::cmp::min(minmax.z_min, z),
             z_max: std::cmp::max(minmax.z_max, z),
+            w_min: std::cmp::min(minmax.w_min, w),
+            w_max: std::cmp::max(minmax.w_max, w),
         }
     });
     let mut new_world = HashSet::new();
     for x in x_min -1 ..= x_max + 1 {
         for  y in y_min -1 ..= y_max + 1 {
             for z in z_min -1 ..= z_max + 1 {
-                let active = world.contains(&(x, y, z));
-                let n = neighbors(&world, (x, y, z));
-                if active && (n == 2 || n == 3) {
-                    new_world.insert((x, y, z));
-                }
-                if !active && n == 3 {
-                    new_world.insert((x, y, z));
+                for w in w_min -1 ..= w_max + 1 {
+                    let active = world.contains(&(x, y, z, w));
+                    let n = neighbors(&world, (x, y, z, w));
+                    if active && (n == 2 || n == 3) {
+                        new_world.insert((x, y, z, w));
+                    }
+                    if !active && n == 3 {
+                        new_world.insert((x, y, z, w));
+                    }
                 }
             }
         }