day 14 solution

2018/day14/Cargo.lock

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+[[package]]
+name = "day14"
+version = "0.1.0"
+

2018/day14/Cargo.toml

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+[package]
+name = "day14"
+version = "0.1.0"
+authors = ["Andrew Coleman <penguincoder@gmail.com>"]
+edition = "2018"
+
+[dependencies]

2018/day14/input

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+939601

2018/day14/src/main.rs

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