94 lines
2.7 KiB
Rust
94 lines
2.7 KiB
Rust
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use crate::common::AdventOfCodeDay;
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pub struct Day13 {
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input_time: u32,
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input_bus: Vec<Option<u32>>,
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}
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impl Day13 {
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pub fn new() -> Self {
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let input_bytes = include_bytes!("../res/13_input.txt");
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let input_str = String::from_utf8_lossy(input_bytes);
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let t = input_str.lines().next().unwrap().parse::<u32>().unwrap();
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let b = input_str.lines().skip(1).next().unwrap().split(',').map(|p| p.parse::<u32>().ok()).collect::<Vec<Option<u32>>>();
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Self {
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input_time: t,
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input_bus: b,
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}
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}
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fn ext_euclid(a: i128, b: i128) -> (i128, i128, i128) {
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if a == 0 {
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return (b, 0, 1);
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}
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let (gcd, x1, y1) = Day13::ext_euclid(b%a, a);
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let x = y1 - (b/a) * x1;
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let y = x1;
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return (gcd, x, y);
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}
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}
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impl AdventOfCodeDay for Day13 {
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fn task_1(&self) -> String {
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let mut b = self.input_bus
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.iter()
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.flat_map(|p| p.iter())
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.map(|p| *p)
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.collect::<Vec<u32>>();
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b.sort_by(|a,b| (self.input_time % b).cmp(&(self.input_time % a)));
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verboseln!("{}", self.input_time);
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verboseln!("{:?}", b);
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verboseln!("{:?}", b.iter().map(|p| p - self.input_time % p).collect::<Vec<u32>>());
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return (b[0] * (b[0] - self.input_time % b[0])).to_string();
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}
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fn task_2(&self) -> String {
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// https://en.wikipedia.org/wiki/Chinese_remainder_theorem
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// https://mathepedia.de/Chinesischer_Restsatz.html
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let formulas = self.input_bus
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.iter()
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.enumerate()
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.filter(|(_,p)| p.is_some())
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.map(|(i,p)| (i, p.unwrap()))
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.map(|(i,p)| ((-(i as i128) % p as i128 + p as i128) as i128 % p as i128, p as i128))
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.collect::<Vec<(i128, i128)>>();
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if is_verbose!() {
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verboseln!();
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//for (i,b) in &formulas { verboseln!("t = {: <3} | {: <3}", i, b); }
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for (i,b) in &formulas { verboseln!("t % {: <3} = {: <3}", b, i); }
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verboseln!();
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}
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let mut m = 1;
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for (_, mi) in &formulas { m *= mi; }
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let mut x = 0;
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for (ai, mi) in &formulas {
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let (gcd, ri, si) = Day13::ext_euclid(*mi as i128, m / *mi as i128);
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let ei = si * (m / *mi as i128);
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x += ai * ei;
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verbosedbg!(m, m / *mi as i128, ai, mi, gcd, ri, si, ei, x);
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verboseln!();
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}
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x = ((x % m) + m) % m;
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return x.to_string() //TODO
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}
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}
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