From 0091045fb2405f841decd4c34003d337193717af Mon Sep 17 00:00:00 2001
From: kageru <kageru@encode.moe>
Date: Tue, 20 Dec 2022 22:39:21 +0100
Subject: [PATCH] add 2022/20/2

---
 2022/src/bin/day20.rs | 40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/2022/src/bin/day20.rs b/2022/src/bin/day20.rs
index 47c1dff..2bae073 100644
--- a/2022/src/bin/day20.rs
+++ b/2022/src/bin/day20.rs
@@ -4,14 +4,14 @@ use aoc2022::{boilerplate, common::*};
 use std::{collections::VecDeque, iter::repeat};
 
 const DAY: usize = 20;
-type Parsed = VecDeque<(isize, bool)>;
+type Parsed = Vec<isize>;
 
 fn parse_input(raw: &str) -> Parsed {
-    raw.lines().map(|l| l.parse().unwrap()).zip(repeat(false)).collect()
+    raw.lines().map(|l| l.parse().unwrap()).collect()
 }
 
 fn part1(parsed: &Parsed) -> isize {
-    let mut xs = parsed.to_owned();
+    let mut xs: VecDeque<_> = parsed.iter().copied().zip(repeat(false)).collect();
     let mut moved = 0;
     while moved < parsed.len() {
         let x = xs.pop_front().unwrap();
@@ -33,8 +33,32 @@ fn part1(parsed: &Parsed) -> isize {
     a + b + c
 }
 
-fn part2(parsed: &Parsed) -> usize {
-    unimplemented!()
+const DECRYPTION_KEY: isize = 811589153;
+
+fn part2(parsed: &Parsed) -> isize {
+    let mut xs: VecDeque<_> = parsed.iter().enumerate().map(|(p, x)| (p, x * DECRYPTION_KEY)).collect();
+    for i in 0..10 {
+        dbg!(i, &xs);
+        let mut moved = 0;
+        while moved < parsed.len() {
+            let i = xs.iter().position(|(x, _)| x == &moved).unwrap();
+            xs.rotate_left(i);
+            let x = xs.pop_front().unwrap();
+            let idx = ((x.1 + (xs.len() * 2 * DECRYPTION_KEY as usize) as isize) % xs.len() as isize) as usize;
+            dbg!("Inserting at", idx);
+            xs.insert(idx, x);
+            moved += 1;
+        }
+    }
+    let i = xs.iter().position(|(_, x)| x == &0).unwrap();
+    xs.rotate_left(i);
+    xs.rotate_left(1000 % parsed.len());
+    let a = xs.front().unwrap().1;
+    xs.rotate_left(1000 % parsed.len());
+    let b = xs.front().unwrap().1;
+    xs.rotate_left(1000 % parsed.len());
+    let c = xs.front().unwrap().1;
+    a + b + c
 }
 
 boilerplate! {
@@ -47,9 +71,9 @@ boilerplate! {
 4",
     tests: {
         part1: { TEST_INPUT => 3 },
-        part2: { TEST_INPUT => 0 },
+        part2: { TEST_INPUT => 1623178306 },
     },
     bench1 == 23321,
-    bench2 == 0,
-    bench_parse: VecDeque::len => 5000,
+    bench2 == 1428396909280,
+    bench_parse: Vec::len => 5000,
 }