68 lines
2.4 KiB
Rust
68 lines
2.4 KiB
Rust
use std::collections::HashMap;
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use aoc::input;
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#[derive(Debug)]
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enum Op {
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And(String, String), // left-hand can be an int
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Or(String, String),
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Not(String),
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Lshift(String, u16),
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Rshift(String, u16),
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Value(String), // either int or wire
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}
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fn main() {
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let lines = input::read_lines();
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let mut wiring: HashMap<String, Op> = HashMap::new();
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for line in lines {
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let mut parts = line.split(" -> ");
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let op_text = parts.next().unwrap();
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let target = parts.next().unwrap();
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let op_parts: Vec<&str> = op_text.split_whitespace().collect();
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let op = match op_parts.len() {
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1 => { Op::Value(op_parts[0].to_string()) }
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2 => { Op::Not(op_parts[1].to_string()) }
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3 => { match op_parts[1] {
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"AND" => { Op::And(op_parts[0].to_string(), op_parts[2].to_string()) }
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"OR" => { Op::Or(op_parts[0].to_string(), op_parts[2].to_string()) }
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"LSHIFT" => { Op::Lshift(op_parts[0].to_string(), op_parts[2].parse::<u16>().unwrap()) }
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"RSHIFT" => { Op::Rshift(op_parts[0].to_string(), op_parts[2].parse::<u16>().unwrap()) }
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_ => panic!()
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} }
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_ => panic!()
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};
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wiring.insert(target.to_string(), op);
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}
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// Part 1
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let mut cache: HashMap<String, u16> = HashMap::new();
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let part1 = solve(&wiring, "a", &mut cache);
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println!("Wire a: {}", part1);
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// Part 2
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wiring.insert("b".to_string(), Op::Value(part1.to_string()));
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let mut cache: HashMap<String, u16> = HashMap::new();
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println!("Wire a with b overridden: {}", solve(&wiring, "a", &mut cache));
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}
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fn solve(wiring: &HashMap<String, Op>, name: &str, cache: &mut HashMap<String, u16>) -> u16 {
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if cache.contains_key(name) {
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return *cache.get(name).unwrap()
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}
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let value = if let Ok(value) = name.parse::<u16>() {
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return value
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} else {
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match wiring.get(name).unwrap() {
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Op::And(lh, rh) => { solve(wiring, lh, cache) & solve(wiring, rh, cache) }
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Op::Or(lh, rh) => { solve(wiring, lh, cache) | solve(wiring, rh, cache) }
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Op::Not(op) => { !solve(wiring, op, cache) }
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Op::Lshift(lh, rh) => { solve(wiring, lh, cache) << rh }
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Op::Rshift(lh, rh) => { solve(wiring, lh, cache) >> rh }
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Op::Value(v) => { solve(wiring, v, cache) }
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}
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};
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cache.insert(name.to_string(), value);
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value
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}
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