From 4477e24c62e3c010ce3d177c632b052d906e011b Mon Sep 17 00:00:00 2001
From: Raphael Goulais <raphael.goulais@f5c.fr>
Date: Fri, 15 Dec 2023 07:05:58 +0100
Subject: [PATCH] feat: Day 15

---
 README.md            |  3 +-
 data/examples/15.txt |  1 +
 src/bin/15.rs        | 94 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 data/examples/15.txt
 create mode 100644 src/bin/15.rs

diff --git a/README.md b/README.md
index 6cfea14..a321ed7 100644
--- a/README.md
+++ b/README.md
@@ -15,8 +15,9 @@ Solutions for [Advent of Code](https://adventofcode.com/) in [Rust](https://www.
 | [Day 12](./src/bin/12.rs) | `358.8µs` | `770.0µs` |
 | [Day 13](./src/bin/13.rs) | `412.9µs` | `894.6µs` |
 | [Day 14](./src/bin/14.rs) | `39.9µs` | `26.5ms` |
+| [Day 15](./src/bin/15.rs) | `52.4µs` | `1.3ms` |
 
-**Total: 29.17ms**
+**Total: 30.52ms**
 <!--- benchmarking table --->
 
 ---
diff --git a/data/examples/15.txt b/data/examples/15.txt
new file mode 100644
index 0000000..62f7ed0
--- /dev/null
+++ b/data/examples/15.txt
@@ -0,0 +1 @@
+rn=1,cm-,qp=3,cm=2,qp-,pc=4,ot=9,ab=5,pc-,pc=6,ot=7
\ No newline at end of file
diff --git a/src/bin/15.rs b/src/bin/15.rs
new file mode 100644
index 0000000..3387803
--- /dev/null
+++ b/src/bin/15.rs
@@ -0,0 +1,94 @@
+advent_of_code::solution!(15);
+
+use std::collections::HashMap;
+
+pub struct Boxes {
+    keys: Vec<String>,
+    map: HashMap<String, u32>,
+}
+
+impl Boxes {
+    pub fn new() -> Self {
+        Self {
+            keys: Vec::new(),
+            map: HashMap::new(),
+        }
+    }
+
+    pub fn insert(&mut self, key: String, value: u32) {
+        if !self.map.contains_key(&key) {
+            self.keys.push(key.clone());
+        }
+        self.map.insert(key, value);
+    }
+
+    pub fn update(&mut self, key: String, value: u32) {
+        if self.map.contains_key(&key) {
+            self.map.insert(key, value);
+        }
+    }
+
+    pub fn remove(&mut self, key: &String) {
+        self.keys.retain(|k| k != key);
+        self.map.remove(key);
+    }
+}
+
+
+fn hash_algo(input_string: &str) -> u32 {
+    let mut current_value: u32 = 0;
+    for char in input_string.chars() {
+        let ascii_value = char as u32;
+        current_value += ascii_value;
+        current_value *= 17;
+        current_value %= 256;
+    }
+    current_value
+}
+
+pub fn part_one(input: &str) -> Option<u32> {
+    let mut current_value: u32 = 0;
+    for line in input.split(",") {
+        current_value += hash_algo(line);
+    }
+    Some(current_value)
+}
+
+pub fn part_two(input: &str) -> Option<u32> {
+    let mut current_value: u32 = 0;
+    let mut boxes = Boxes::new();
+    for line in input.split(",") {
+        if line.ends_with('-') {
+            boxes.remove(&line[0..line.len() - 1].to_string());
+        } else {
+            let (key, value) = line.split_at(line.find('=').unwrap());
+            boxes.insert(key.to_string(), value[1..].parse::<u32>().unwrap());
+        }
+    }
+    let mut slots: HashMap<u32, u32> = HashMap::with_capacity(256);
+    for key in boxes.keys {
+        let val = boxes.map.get(&key).unwrap();
+        let box_number = hash_algo(&key);
+        let slot = slots.entry(box_number).or_insert(0);
+        *slot += 1;
+        current_value += (box_number + 1) * *slot * val;
+    }
+    Some(current_value)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_part_one() {
+        let result = part_one(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(1320));
+    }
+
+    #[test]
+    fn test_part_two() {
+        let result = part_two(&advent_of_code::template::read_file("examples", DAY));
+        assert_eq!(result, Some(145));
+    }
+}