day15: rust

15/README.md

@@ -0,0 +1,16 @@
+# [Day 15](https://adventofcode.com/2023/day/15) 
+:gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift::gift:
+
+Today's language: **Rust**
+
+Lines of code: **54**
+
+Execution time: **0,002 s**
+
+What a nice name: Holiday ASCII String Helper Manual Arrangement Procedure
+
+```shell
+rustc +nightly day15.rs
+./day15
+```
+<!-- hashmap -->

15/day15.rs

@@ -0,0 +1,66 @@
+#![feature(extract_if)]
+use std::io::{self, BufRead};
+use std::collections::LinkedList;
+use std::str::FromStr;
+
+// tilt so that all 'O' characters want to DECREMENT their Y index
+// using custom `at` function that "remaps" x and y, this function can be used for all directions
+fn ascii_hash(s: &str) -> usize {
+    let mut hash: usize = 0;
+    for c in s.as_bytes().iter() {
+        hash += *c as usize;
+        hash *= 17;
+        hash %= 256;
+    }
+    return hash;
+}
+
+fn print(boxes: &Vec<LinkedList<(String, u8)>>) {
+    for (i, l) in boxes.iter().enumerate() {
+        if l.is_empty() { continue;}
+        print!("Box {}: ", i);
+        for t in l.iter() {
+            print!("[{} {}] ", t.0, t.1);
+        }
+        println!();
+    }
+}
+
+
+fn main() {
+    // let input = "example.txt";
+    let input = "input.txt";
+    let mut lines = read_lines(&input);
+    let mut hash_sum: usize = 0;
+    let mut boxes = vec![LinkedList::<(String, u8)>::new(); 256];
+    for s in lines.next().expect("Line not ok").unwrap().split(',') {
+        hash_sum += ascii_hash(&s) as usize;
+        if *s.as_bytes().last().unwrap() == b'-' {
+            let hash = ascii_hash(&s[..s.len()-1]);
+            let _ = boxes[hash].extract_if(|t| t.0 == &s[..s.len()-1]).for_each(drop);
+        }
+        else { 
+            let hash = ascii_hash(&s[..s.len()-2]);
+            let focal_length = s[s.len()-1..].parse::<u8>().unwrap();
+            if let Some(t) = boxes[hash].iter_mut().filter(|t| t.0 == &s[..s.len()-2]).next() {
+                t.1 = focal_length; 
+            }
+            else {
+                boxes[hash].push_back((String::from_str(&s[..s.len()-2]).expect("String err"), focal_length));
+            }
+        }
+        // println!("\nAfter \"{}\"", s);
+        // print(&boxes);
+    }
+    println!("Hash sum (1): {}", hash_sum);
+    println!("Focus power sum (2): {}", boxes.iter().enumerate().map(|(b, l)| l.iter().enumerate().map(|(i, t)| (b+1) * (i+1) * t.1 as usize).sum::<usize>()).sum::<usize>());
+}
+
+fn read_lines<P>(filename: P) -> io::Lines<io::BufReader<std::fs::File>>
+where P: AsRef<std::path::Path>, {
+    return match std::fs::File::open(filename) {
+        Err(why) => panic!("Could not open file. {}", why),
+        Ok(file) => std::io::BufReader::new(file).lines()
+    };
+}
+

README.md

@@ -17,5 +17,6 @@ This is a repository for my solutions for the [advent of code 2023](https://adve
 | [11](11) | Rust     | 66            | 0,005 s         |                               |
 | [13](13) | Rust     | 84            | 0,002 s         | binary encoding ftw           |
 | [14](14) | Rust     | 85            | 0,172 s         | no bruteforce in < 90 lines   |
+| [15](15) | Rust     | 54            | 0,002 s         | hashmap                       |
 
  Lines of code are without blank lines and comments