129 lines
3.9 KiB
Rust
129 lines
3.9 KiB
Rust
const INPUT: &str = include_str!("../../data/day14/input");
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use std::collections::HashMap;
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#[derive(Clone, Copy, Debug, Default)]
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pub struct Mask {
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fixed: u64,
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select_value: u64,
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}
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impl Mask {
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pub fn parse(data: &str) -> Self {
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let (fixed, select_value) = data.trim().chars().fold((0, 0), |(fixed, select), c| {
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match c {
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'0' => (2*fixed + 0, 2*select + 0),
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'1' => (2*fixed + 1, 2*select + 0),
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'X' => (2*fixed + 0, 2*select + 1),
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_ => panic!("invalid mask character: {:?}", c),
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}
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});
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assert_eq!(0, select_value & fixed);
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Self { fixed, select_value }
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}
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pub fn apply(self, value: u64) -> u64 {
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self.fixed | (self.select_value & value)
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}
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}
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#[derive(Clone, Debug, Default)]
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pub struct Fluctuations {
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clear: u64,
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flucts: Vec<u64>,
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}
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impl Fluctuations {
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pub fn apply(&self, address: u64) -> impl Iterator<Item = u64> + '_ {
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let address = address & !self.clear;
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self.flucts.iter().map(move |&mask| mask | address)
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}
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}
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impl From<Mask> for Fluctuations {
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fn from(mask: Mask) -> Self {
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let mut flucts = vec![mask.fixed];
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let mut fluct = mask.select_value;
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let mut current = 0;
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// println!("fluctuate : {:036b}", fluct);
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while 0 != fluct {
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let shift = fluct.trailing_zeros();
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current += shift;
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let bit = 1 << current;
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// println!("extending with bit: {:036b}", bit);
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let new_flucts = flucts.iter().map(|&m| m | bit).collect::<Vec<_>>();
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flucts.extend(new_flucts);
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current += 1;
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fluct = fluct >> (shift + 1);
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}
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Self {
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clear: mask.select_value,
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flucts,
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}
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}
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}
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#[derive(Clone, Copy, Debug)]
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pub enum Instruction {
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SetMask { mask: Mask },
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SetMemory { address: u64, value: u64 },
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}
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impl Instruction {
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pub fn parse(line: &str) -> Self {
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if let Some(rem) = line.strip_prefix("mask = ") {
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let mask = Mask::parse(rem);
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Self::SetMask { mask }
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} else if let Some(rem) = line.strip_prefix("mem[") {
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let p = rem.find("] = ").unwrap();
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let address = &rem[..p];
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let address = address.parse().unwrap_or_else(|e| panic!("invalid address: {:?}: {}", address, e));
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let value = &rem[p+4..];
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let value = value.parse().unwrap_or_else(|e| panic!("invalid value: {:?}: {}", value, e));
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Self::SetMemory { address, value }
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} else {
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panic!("invalid input: {:?}", line);
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}
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}
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pub fn parse_list(input: &str) -> Vec<Self> {
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input.lines().map(Self::parse).collect()
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}
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}
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fn main() {
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let instructions = Instruction::parse_list(INPUT);
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{
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let mut memory = HashMap::new();
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let mut current_mask = Mask::default();
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for instr in &instructions {
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match *instr {
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Instruction::SetMask { mask } => {
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current_mask = mask;
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},
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Instruction::SetMemory { address, value } => {
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memory.insert(address, current_mask.apply(value));
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},
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}
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}
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println!("Sum of values: {}", memory.values().sum::<u64>());
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}
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{
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let mut memory = HashMap::new();
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let mut flucts = Fluctuations::default();
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for instr in &instructions {
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match *instr {
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Instruction::SetMask { mask } => {
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flucts = Fluctuations::from(mask);
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},
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Instruction::SetMemory { address, value } => {
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for address in flucts.apply(address) {
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memory.insert(address, value);
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}
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},
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}
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}
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println!("Sum of values: {}", memory.values().sum::<u64>());
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}
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}
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