76 lines
2.0 KiB
Rust
76 lines
2.0 KiB
Rust
use aoc_runner_derive::{aoc, aoc_generator};
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type Input = Vec<usize>;
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#[aoc_generator(day22)]
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fn parse(input: &str) -> Input {
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input.lines().map(|n| n.parse().unwrap()).collect()
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}
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#[inline(always)]
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fn next_number(number: usize) -> usize {
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let step1 = (number ^ (number << 6)) % (1 << 24);
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let step2 = (step1 ^ (step1 >> 5)) % (1 << 24);
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(step2 ^ step2 << 11) % (1 << 24)
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}
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#[inline(always)]
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fn step_2000(number: usize) -> usize {
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let mut number = number;
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for _ in 0..2000 {
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number = next_number(number);
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}
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number
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}
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#[aoc(day22, part1)]
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fn part1(input: &Input) -> usize {
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input.iter().map(|n| step_2000(*n)).sum()
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}
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#[aoc(day22, part2)]
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fn part2(input: &Input) -> usize {
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let mut total = Box::new([[[[0; 19]; 19]; 19]; 19]);
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let mut max_total = 0;
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let mut last_monkey = Box::new([[[[0; 19]; 19]; 19]; 19]);
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for (monkey, secret) in input.iter().enumerate() {
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let mut one = *secret;
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let mut two = next_number(one);
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let mut three = next_number(two);
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let mut four = next_number(three);
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for _ in 0..2000 - 3 {
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let next = next_number(four);
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let idx_1 = (two % 10) - (one % 10) + 9;
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let idx_2 = (three % 10) - (two % 10) + 9;
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let idx_3 = (four % 10) - (three % 10) + 9;
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let idx_4 = (next % 10) - (four % 10) + 9;
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if last_monkey[idx_1][idx_2][idx_3][idx_4] <= monkey {
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last_monkey[idx_1][idx_2][idx_3][idx_4] = monkey + 1;
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total[idx_1][idx_2][idx_3][idx_4] += next % 10;
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max_total = max_total.max(total[idx_1][idx_2][idx_3][idx_4]);
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}
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one = two;
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two = three;
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three = four;
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four = next;
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}
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}
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max_total
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn part1_example() {
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assert_eq!(part1(&parse("1")), 8685429);
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assert_eq!(part1(&parse("10")), 4700978);
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assert_eq!(part1(&parse("100")), 15273692);
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assert_eq!(part1(&parse("2024")), 8667524);
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}
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}
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