From afb41b247fcc23509d63b5795dfb8c85a317c6f1 Mon Sep 17 00:00:00 2001
From: Toby Vincent <tobyv@tobyvin.dev>
Date: Thu, 21 Dec 2023 01:18:42 -0600
Subject: perf(wip): attempt to improve day 18

---
 src/day_18.rs | 45 ++++++++++++++++++++++++++++-----------------
 1 file changed, 28 insertions(+), 17 deletions(-)

(limited to 'src')

diff --git a/src/day_18.rs b/src/day_18.rs
index 1ed5100..aa2bdf1 100644
--- a/src/day_18.rs
+++ b/src/day_18.rs
@@ -71,15 +71,15 @@ impl Solution for Day18 {
     }
 
     fn part_2(input: &str) -> anyhow::Result<Self::Answer2> {
-        let mut pos = (0_isize, 0_isize);
-        let mut trenches = vec![(pos, 'S')];
+        let mut trenches = vec![];
 
+        let mut pos = (0_isize, 0_isize);
+        let mut dir = 'D';
         let mut b = 0;
-        let mut dir = 'S';
 
         for line in input.lines() {
             let (c, len) = parse_code(line);
-            b += len;
+            b += len as usize;
 
             if "DU".contains(c) && dir != c {
                 dir = c;
@@ -88,17 +88,28 @@ impl Solution for Day18 {
                 }
             }
 
-            for _ in 0..len {
-                match c {
-                    'U' => pos.0 -= 1,
-                    'D' => pos.0 += 1,
-                    'L' => pos.1 -= 1,
-                    'R' => pos.1 += 1,
-                    c => return Err(anyhow::format_err!("Invalid character: {c}")),
-                };
-
-                trenches.push((pos, dir));
-            }
+            // for _ in 0..len {
+            //     match c {
+            //         'U' => pos.0 -= 1,
+            //         'D' => pos.0 += 1,
+            //         'L' => pos.1 -= 1,
+            //         'R' => pos.1 += 1,
+            //         c => return Err(anyhow::format_err!("Invalid character: {c}")),
+            //     };
+            //
+            //     trenches.push((pos, dir));
+            // }
+            trenches.push(((pos.0, pos.1), dir));
+
+            match c {
+                'U' => (1..len).for_each(|n| trenches.push(((pos.0 - n, pos.1), dir))),
+                'D' => (1..len).for_each(|n| trenches.push(((pos.0 + n, pos.1), dir))),
+                'L' => trenches.push(((pos.0, pos.1 - len), dir)),
+                'R' => trenches.push(((pos.0, pos.1 + len), dir)),
+                c => return Err(anyhow::format_err!("Invalid character: {c}")),
+            };
+
+            pos = *trenches.last().map(|(p, _)| p).unwrap();
         }
 
         trenches.sort();
@@ -122,7 +133,7 @@ impl Solution for Day18 {
     }
 }
 
-fn parse_code(s: &str) -> (char, usize) {
+fn parse_code(s: &str) -> (char, isize) {
     let iter = &mut s
         .split_whitespace()
         .nth(2)
@@ -132,7 +143,7 @@ fn parse_code(s: &str) -> (char, usize) {
         .strip_suffix(')')
         .unwrap()
         .chars();
-    let dist = usize::from_str_radix(&iter.take(5).collect::<String>(), 16).unwrap();
+    let dist = isize::from_str_radix(&iter.take(5).collect::<String>(), 16).unwrap();
     let code = iter.next().unwrap().to_digit(10).unwrap();
     let c = match code {
         0 => 'R',
-- 
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