52 lines
1.5 KiB
Rust
52 lines
1.5 KiB
Rust
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use std::fs::File;
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use std::io::{BufRead, BufReader};
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fn mutate_chocolate(scores: &mut Vec<u8>, recipes: i32) -> (String, usize) {
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let mut elf1: usize = 0;
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let mut elf2: usize = 1;
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loop {
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let elf1score = scores[elf1];
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let elf2score = scores[elf2];
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let sum = elf1score + elf2score;
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let sum_str = format!("{}", sum);
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for c in sum_str.chars() {
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scores.push(c as u8 - 48);
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}
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if scores.len() > recipes as usize + 100000000 {
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break;
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}
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elf1 = (elf1 + (1 + elf1score as usize)) % scores.len();
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elf2 = (elf2 + (1 + elf2score as usize)) % scores.len();
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}
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let mut result = String::new();
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for i in 0..10 {
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result.push((scores[recipes as usize + i] + 48) as char);
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}
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let mut score_str = String::with_capacity(scores.len());
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for s in scores.iter() {
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score_str.push((s + 48) as char);
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}
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let recipe_str = format!("{}", recipes);
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let recipe_index = score_str.find(recipe_str.as_str()).unwrap();
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(result, recipe_index)
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}
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fn main() {
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let mut line = String::new();
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BufReader::new(File::open("input").unwrap())
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.read_line(&mut line)
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.unwrap();
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let recipes = line.trim().parse::<i32>().unwrap();
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let mut scores: Vec<u8> = Vec::with_capacity(1000000);
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scores.push(3);
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scores.push(7);
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let (final_score, final_index) = mutate_chocolate(&mut scores.clone(), recipes);
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println!("part 1 final score {}", final_score);
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println!("recipe repeated at index {}", final_index);
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}
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