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www.mikescher.com/www/statics/aoc/2020/25_solution.rs

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2020-12-25 16:39:04 +01:00
use crate::common::AdventOfCodeDay;
pub struct Day25 {
pkey_card: u64,
pkey_door: u64,
}
impl Day25 {
pub fn new() -> Self {
let input_bytes = include_bytes!("../res/25_input.txt");
let input_str = String::from_utf8_lossy(input_bytes);
let lines = input_str
.lines()
.map(|p| String::from(p))
.map(|p| p.parse::<u64>().unwrap())
.collect::<Vec<_>>();
Self {
pkey_card: lines[0],
pkey_door: lines[1],
}
}
}
impl Day25 {
fn transform(subjectnumber: u64, loopcount: usize) -> u64 {
let mut v = 1;
for _ in 0..loopcount {
v *= subjectnumber;
v %= 20201227;
}
return v;
}
fn transform_back(subjectnumber: u64, pkey_dest: u64) -> usize {
let mut v = 1;
for lc in 1.. {
v *= subjectnumber;
v %= 20201227;
if v == pkey_dest {
return lc;
}
}
panic!();
}
}
impl AdventOfCodeDay for Day25 {
fn task_1(&self) -> String {
verboseln!("card public key: {}", self.pkey_card);
verboseln!("door public key: {}", self.pkey_door);
verboseln!();
let loopsize_card = Self::transform_back(7, self.pkey_card);
verboseln!("card loop size: {}", loopsize_card);
let loopsize_door = Self::transform_back(7, self.pkey_door);
verboseln!("door loop size: {}", loopsize_door);
verboseln!();
let skey_card = Self::transform(self.pkey_card, loopsize_door);
verboseln!("card encryption key: {}", skey_card);
let skey_door = Self::transform(self.pkey_door, loopsize_card);
verboseln!("door encryption key: {}", skey_door);
verboseln!();
return skey_card.to_string().to_owned();
}
fn task_2(&self) -> String {
return "".to_owned()
}
}