From e2931282dca4bbd06e0902c444c6428f98f9607a Mon Sep 17 00:00:00 2001
From: Bas Dado <bas@orbitgames.nl>
Date: Tue, 29 Dec 2020 22:19:21 +0100
Subject: [PATCH] [TASK] Solved Day 23 Pt 1

---
 input/day23.txt         |  1 +
 input/day23_example.txt |  1 +
 src/day21.rs            |  2 +-
 src/day23.rs            | 84 +++++++++++++++++++++++++++++++++++++++++
 src/main.rs             |  4 +-
 5 files changed, 90 insertions(+), 2 deletions(-)
 create mode 100644 input/day23.txt
 create mode 100644 input/day23_example.txt
 create mode 100644 src/day23.rs

diff --git a/input/day23.txt b/input/day23.txt
new file mode 100644
index 0000000..0f6ac81
--- /dev/null
+++ b/input/day23.txt
@@ -0,0 +1 @@
+186524973
\ No newline at end of file
diff --git a/input/day23_example.txt b/input/day23_example.txt
new file mode 100644
index 0000000..7a64a0a
--- /dev/null
+++ b/input/day23_example.txt
@@ -0,0 +1 @@
+389125467
\ No newline at end of file
diff --git a/src/day21.rs b/src/day21.rs
index a469a28..48da2cf 100644
--- a/src/day21.rs
+++ b/src/day21.rs
@@ -31,7 +31,7 @@ pub fn solve() {
         possible_ingredients_per_allergen.insert(allergen, matching_ingredients);
     }
 
-    println!("{:?}", possible_ingredients_per_allergen);
+    // println!("{:?}", possible_ingredients_per_allergen);
 
     // Now all the ingredients that are not "possible ingredients per allergen" can not possibly contain an allergen, so we count those instances:
     let allergy_ingredients: HashSet<&String> = HashSet::from_iter(possible_ingredients_per_allergen.iter()
diff --git a/src/day23.rs b/src/day23.rs
new file mode 100644
index 0000000..6cc97ee
--- /dev/null
+++ b/src/day23.rs
@@ -0,0 +1,84 @@
+use super::util;
+use std::collections::LinkedList;
+use std::iter::FromIterator;
+use std::convert::TryFrom;
+use std::intrinsics::copy;
+
+pub fn solve() {
+    let lines = util::read_file("input/day23.txt");
+    let input = lines.first().unwrap().chars().map(|c| (c  as u8 - '0' as u8)).collect::<Vec<u8>>();
+
+    let result = play_game(<&[u8; 9]>::try_from(&input[0..]).unwrap(), 100);
+    let part1 = reorder_starting_from(&result, 1).iter().take(8).map(|s| s.to_string()).collect::<Vec<String>>().join("");
+    println!("Day 23 Part 1: {}", part1);
+
+
+    let part2 = 0;
+    println!("Day 23 Part 2: {}", part2);
+}
+
+fn play_game(input: &[u8; 9], rounds: u64) -> [u8; 9] {
+
+    let max_cup = input.iter().max().unwrap().clone();
+    let min_cup = input.iter().min().unwrap().clone();
+    let len = input.len();
+    let mut cur_order = input.clone();
+    let mut next_order = input.clone();
+    let mut cur_idx = 0usize;
+    for _ in 0..rounds {
+
+        let cur_label = &cur_order[cur_idx];
+        let mut dest_label = if cur_label == &min_cup { max_cup } else { cur_label - 1 };
+        let mut dest_idx = index_of(&cur_order, &dest_label);
+        let mut looped_dest_idx = if dest_idx < cur_idx { dest_idx + input.len() } else { dest_idx };
+
+        while looped_dest_idx > cur_idx && looped_dest_idx <= cur_idx + 3 {
+            dest_label = if dest_label == min_cup { max_cup } else { dest_label - 1 };
+            dest_idx = index_of(&cur_order, &dest_label);
+            looped_dest_idx = if dest_idx < cur_idx { dest_idx + input.len() } else { dest_idx };
+        }
+
+
+        // First copy the part from the end of the "picked up" cups to the destination
+        for i in cur_idx + 4..looped_dest_idx + 1 {
+            next_order[(i - 3) % len] = cur_order[i % len];
+        }
+
+        // Then copy the picked up cups to the destination
+        for i in 0..3 {
+            next_order[(looped_dest_idx - 2 + i) % len] = cur_order[(cur_idx + 1 + i) % len];
+        }
+
+        // println!("{:?}", next_order);
+        for c in input {
+            assert!(next_order.contains(c), format!("Lost {} while playing with index {} and destination label {}, dest index {}", c, cur_idx, dest_label, dest_idx));
+        }
+
+        // The rest should already be in the correct order
+        cur_order = next_order.clone();
+
+        cur_idx = (cur_idx + 1) % input.len();
+    }
+
+    return cur_order;
+}
+
+fn index_of(cups: &[u8;9], cup: &u8) -> usize {
+    for i in 0..cups.len() {
+        if &cups[i] == cup {
+            return i;
+        }
+    }
+    panic!(format!("Couldn't find {}", cup));
+}
+
+fn reorder_starting_from(cups: &[u8; 9], n:u8) -> [u8; 9] {
+
+    let n_idx = index_of(cups, &n);
+    let mut res = [0u8; 9];
+    for i in 0..9 {
+        res[i] = cups[(n_idx + 1 + i) % cups.len()];
+    }
+    return res;
+
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index fee3838..a549154 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -24,8 +24,9 @@ mod day19;
 mod day20;
 mod day21;
 mod day22;
+mod day23;
 
-const MAX_DAY: u8 = 22;
+const MAX_DAY: u8 = 23;
 const BENCHMARK_AMOUNT: u32 = 100;
 
 fn solve(day: u8) {
@@ -52,6 +53,7 @@ fn solve(day: u8) {
         20 => day20::solve(),
         21 => day21::solve(),
         22 => day22::solve(),
+        23 => day23::solve(),
         _ => println!("This day is not yet implemented")
     }
 }