From 97368dc1d97fd3a519d712e1039811cba428755d Mon Sep 17 00:00:00 2001
From: Dave Farnham <dave.farnham@icloud.com>
Date: Thu, 9 Jan 2025 15:22:07 -0700
Subject: [PATCH] Update day16.rs
This isn't a proposed final fix, just an attempt to show the overflow error my input generates.
This is repository is absolutely spectacular!
Please feel free to reach out for more details if needed.
---
src/year2024/day16.rs | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)
diff --git a/src/year2024/day16.rs b/src/year2024/day16.rs
index 449db1a..269e87b 100644
--- a/src/year2024/day16.rs
+++ b/src/year2024/day16.rs
@@ -89,10 +89,36 @@ pub fn parse(input: &str) -> Input {
// Reverse direction and subtract cost.
let left = (direction + 3) % 4;
let right = (direction + 1) % 4;
+
+ // println!("cost = {cost}, lowest = {lowest}, path.bytes...count() = {}", path.bytes.iter().filter(|&&b| b).count());
let next = [
(position - DIRECTIONS[direction], direction, cost - 1),
- (position, left, cost - 1000),
- (position, right, cost - 1000),
+ //
+ // This isn't a clever or performant fix, but prevents the: "attempt to subtract with overflow" error for my input.
+ //
+ // I think the correct fix is to capture the length of the initial "same direction" moves from the start
+ // and add that length to the final result without processing that part of the path here??
+ //
+ // Hopefully this little bit of debug output before the panic will suffice.
+ // The correct answer for my input is 467
+ //
+ // cost = 1005, lowest = 83432, path.bytes...count() = 462
+ // cost = 1004, lowest = 83432, path.bytes...count() = 463
+ // cost = 4, lowest = 83432, path.bytes...count() = 463
+ // cost = 3, lowest = 83432, path.bytes...count() = 464
+ // cost = 2, lowest = 83432, path.bytes...count() = 465
+ // cost = 1, lowest = 83432, path.bytes...count() = 466
+ // 2024 Day 16
+ // Part 1: 83432
+ // Part 2: 467
+ (position, left, match cost {
+ 0..1000 => 0,
+ _ => cost - 1000
+ }),
+ (position, right, match cost {
+ 0..1000 => 0,
+ _ => cost - 1000
+ }),
];
for (next_position, next_direction, next_cost) in next {