91 lines
2.3 KiB
Rust
91 lines
2.3 KiB
Rust
use std::fs;
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use std::path::Path;
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#[derive(Debug)]
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pub enum Instruction {
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Mul(u64, u64),
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}
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#[derive(Debug)]
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pub enum ParserState {
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ParseAny,
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ParseIdent(Ident),
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ParseNumber(u32, [Vec<u32>; 2]),
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}
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#[derive(Debug)]
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pub enum Ident {
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Mul(u32),
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}
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#[derive(Debug)]
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pub struct PuzzleInput {
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pub instructions: Vec<Instruction>,
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}
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impl PuzzleInput {
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pub fn parse<P>(path: P) -> Self
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where
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P: AsRef<Path>,
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{
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let content = fs::read_to_string(path).unwrap();
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let mut instructions = Vec::new();
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let mut state = ParserState::ParseAny;
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for ch in content.chars() {
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state = match (ch, state) {
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('m', ParserState::ParseIdent(Ident::Mul(0)) | ParserState::ParseAny) => {
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ParserState::ParseIdent(Ident::Mul(1))
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}
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('u', ParserState::ParseIdent(Ident::Mul(1))) => {
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ParserState::ParseIdent(Ident::Mul(2))
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}
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('l', ParserState::ParseIdent(Ident::Mul(2))) => {
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ParserState::ParseIdent(Ident::Mul(3))
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}
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('(', ParserState::ParseIdent(Ident::Mul(3))) => {
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ParserState::ParseNumber(0, [vec![], vec![]])
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}
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(',', ParserState::ParseNumber(0, nums)) => ParserState::ParseNumber(1, nums),
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(')', ParserState::ParseNumber(1, nums)) => {
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let nums = numbers_from_slice(&nums);
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instructions.push(Instruction::Mul(nums[0], nums[1]));
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ParserState::ParseAny
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}
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('0'..='9', ParserState::ParseNumber(n, mut nums)) => {
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let digit = ch.to_digit(10).unwrap();
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nums[n as usize].push(digit);
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ParserState::ParseNumber(n, nums)
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}
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_ => ParserState::ParseAny,
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}
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}
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Self { instructions }
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}
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}
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fn numbers_from_slice(numbers: &[Vec<u32>]) -> Vec<u64> {
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const RADIX: u64 = 10;
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let mut converted = Vec::new();
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for number in numbers {
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let mut tmp_num = 0;
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for (digits, n) in number.into_iter().rev().enumerate() {
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tmp_num += (*n as u64) * RADIX.pow(digits as u32);
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}
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converted.push(tmp_num);
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}
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converted
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}
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