From c17be699102490330e0a795b6405bbe3441b66a6 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Sun, 9 Dec 2018 13:27:05 +0100
Subject: [PATCH] Replace linkedlist with VecDeq.

Slightly slower but a lot cleaner.
---
 2018/Cargo.toml   |  1 -
 2018/src/day09.rs | 48 +++++++++++++----------------------------------
 2018/src/lib.rs   |  2 --
 3 files changed, 13 insertions(+), 38 deletions(-)

diff --git a/2018/Cargo.toml b/2018/Cargo.toml
index ce108d6..c86bbc0 100644
--- a/2018/Cargo.toml
+++ b/2018/Cargo.toml
@@ -9,4 +9,3 @@ clap = "2.32"
 regex = "1.1.0"
 chrono = "0.4.6"
 itertools = "0.7.11"
-intrusive-collections = "0.7.8"
diff --git a/2018/src/day09.rs b/2018/src/day09.rs
index 3b3734a..108fbe3 100644
--- a/2018/src/day09.rs
+++ b/2018/src/day09.rs
@@ -1,53 +1,31 @@
-use std::cell::Cell;
+use std::collections::VecDeque;
 use std::io::Read;
 
-use intrusive_collections::{LinkedList, LinkedListLink};
-
 use common::Solution;
 
-struct Marble {
-    link: LinkedListLink,
-    value: Cell<usize>,
-}
-
-impl Marble {
-    pub fn new(value: usize) -> Box<Self> {
-        Box::new(Marble {
-            link: LinkedListLink::new(),
-            value: Cell::new(value),
-        })
-    }
-}
-
-intrusive_adapter!(MarbleAdapter = Box<Marble>: Marble { link: LinkedListLink });
-
 fn winning_marbles(elves: usize, marbles: usize) -> usize {
     let mut scores = vec![0usize; elves];
-    let mut state: LinkedList<_> = LinkedList::new(MarbleAdapter::new());
-    state.push_front(Marble::new(0));
-    let mut current = state.front_mut();
+    let mut state = VecDeque::new();
+    state.push_front(0);
 
     for marble in 1..=marbles {
         if marble % 23 == 0 {
             let player = marble % elves;
+
             for _ in 0..7 {
-                current.move_prev();
-                if current.is_null() {
-                    current.move_prev();
-                }
+                let c = state.pop_back().unwrap();
+                state.push_front(c);
             }
 
-            let to_remove = current.get().unwrap().value.get();
+            let removed = state.pop_back().unwrap();
+            scores[player] += removed + marble;
 
-            scores[player] += marble + to_remove;
-            current.remove();
+            let c = state.pop_front().unwrap();
+            state.push_back(c);
         } else {
-            current.move_next();
-            if current.is_null() {
-                current.move_next();
-            }
-            current.insert_after(Marble::new(marble));
-            current.move_next();
+            let c = state.pop_front().unwrap();
+            state.push_back(c);
+            state.push_back(marble);
         }
     }
 
diff --git a/2018/src/lib.rs b/2018/src/lib.rs
index fcd6406..017ae87 100644
--- a/2018/src/lib.rs
+++ b/2018/src/lib.rs
@@ -1,7 +1,5 @@
 extern crate chrono;
 #[macro_use]
-extern crate intrusive_collections;
-#[macro_use]
 extern crate itertools;
 extern crate regex;