From b8fd7080b68176a31a9d6ec6d094a61e41204fe1 Mon Sep 17 00:00:00 2001
From: Sijmen Schoon <me@sijmenschoon.nl>
Date: Fri, 25 Dec 2020 21:12:18 +0100
Subject: [PATCH] rust(day15): Optimize day 15 to ~450 ms

---
 rust/src/day15.rs | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/rust/src/day15.rs b/rust/src/day15.rs
index e8e307c..6234319 100644
--- a/rust/src/day15.rs
+++ b/rust/src/day15.rs
@@ -1,23 +1,24 @@
 use std::time::{Duration, Instant};
+use std::boxed::Box;
 
-const END: usize = 30_000_000;
+const END: u32 = 30_000_000;
 pub fn run(print: bool) -> Duration {
-    let input: Vec<usize> = "0,1,5,10,3,12,19"
+    let input: Vec<u32> = "0,1,5,10,3,12,19"
         .split(",")
         .map(|i| i.parse().unwrap())
         .collect();
     let instant = Instant::now();
 
-    let mut history = vec![0; END];
+    let mut history = vec![0u32; END as usize];
     let mut last = input[0];
-    for turn in 0..input.len() {
-        history[last] = turn;
-        last = input[turn];
+    for turn in 0..input.len() as u32 {
+        history[last as usize] = turn as u32;
+        last = input[turn as usize];
     }
 
-    for turn in input.len()..2020 {
-        let stored = history[last];
-        history[last] = turn;
+    for turn in input.len() as u32..2020 {
+        let stored = history[last as usize];
+        history[last as usize] = turn;
         last = if stored == 0 { 0 } else { turn - stored };
     }
     if print {
@@ -25,8 +26,8 @@ pub fn run(print: bool) -> Duration {
     }
 
     for turn in 2020..END {
-        let stored = history[last];
-        history[last] = turn;
+        let stored = history[last as usize];
+        history[last as usize] = turn;
         last = if stored == 0 { 0 } else { turn - stored };
     }
     if print {