78 lines
2.1 KiB
Rust
78 lines
2.1 KiB
Rust
#![feature(test)]
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extern crate test;
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use aoc2022::{boilerplate, common::*};
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use std::{
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collections::VecDeque,
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iter::{repeat, repeat_with},
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};
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const DAY: usize = 20;
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type Parsed = Vec<isize>;
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fn parse_input(raw: &str) -> Parsed {
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raw.lines().map(|l| l.parse().unwrap()).collect()
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}
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fn part1(parsed: &Parsed) -> isize {
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let mut xs: VecDeque<_> = repeat(false).zip(parsed.iter().copied()).collect();
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let mut moved = 0;
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while moved < parsed.len() {
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let x = xs.pop_front().unwrap();
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if x.0 {
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// already processed, just put it in the back
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xs.push_back(x);
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} else {
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// casting :notLikeMiya:
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xs.insert(((x.1 + (xs.len() * 2) as isize) % xs.len() as isize) as usize, (true, x.1));
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moved += 1;
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}
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}
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get_coords(&mut xs)
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}
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const DECRYPTION_KEY: isize = 811589153;
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fn part2(parsed: &Parsed) -> isize {
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let mut xs: VecDeque<_> = parsed.iter().enumerate().map(|(p, x)| (p, x * DECRYPTION_KEY)).collect();
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// Effective length is reduced by one because the element that’s being moved is no longer in the collection.
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let len = xs.len() as isize - 1;
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// Add this to each element to make it guaranteed positive before modulo-ing for the index.
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let make_positive = len * 2 * DECRYPTION_KEY;
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for _ in 0..10 {
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for current in 0..parsed.len() {
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let i = xs.iter().position(|(x, _)| x == ¤t).unwrap();
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xs.rotate_left(i);
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let x = xs.pop_front().unwrap();
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xs.insert(((x.1 + make_positive) % len) as usize, x);
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}
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}
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get_coords(&mut xs)
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}
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fn get_coords<T>(xs: &mut VecDeque<(T, isize)>) -> isize {
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xs.rotate_left(xs.iter().position(|(_, x)| x == &0).unwrap());
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repeat_with(|| {
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xs.rotate_left(1000 % xs.len());
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xs.front().unwrap().1
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})
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.take(3)
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.sum()
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}
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boilerplate! {
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TEST_INPUT == "1
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2
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-3
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3
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-2
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0
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4",
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tests: {
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part1: { TEST_INPUT => 3 },
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part2: { TEST_INPUT => 1623178306 },
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},
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bench1 == 23321,
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bench2 == 1428396909280,
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bench_parse: Vec::len => 5000,
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}
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