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