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extern crate regex;
use regex::Regex;
use std::io::BufReader;
use std::io::prelude::*;
use std::fs::File;
fn main() {
let program = read_file();
let mut registers: [i32; 4] = [0;4];
registers[2] = 1; //init c to 1
let mut pc: usize = 0;
let cpy_lit = Regex::new(r"cpy ([-\d]+) (a|b|c|d)").unwrap();
let cpy_reg = Regex::new(r"cpy (a|b|c|d) (a|b|c|d)").unwrap();
let inc = Regex::new(r"inc (a|b|c|d)").unwrap();
let dec = Regex::new(r"dec (a|b|c|d)").unwrap();
let jnz_lit = Regex::new(r"jnz ([-\d]+) ([-\d]+)").unwrap();
let jnz_reg = Regex::new(r"jnz (a|b|c|d) ([-\d]+)").unwrap();
while pc < program.len() {
let line = program[pc].as_ref();
let mut pc_next: usize = pc+1;
if cpy_lit.is_match(line) {
let cap = cpy_lit.captures(line).unwrap();
let src: i32 = cap.at(1).unwrap().parse().unwrap();
let dest = to_register_index(cap.at(2).unwrap());
registers[dest] = src;
}
else if cpy_reg.is_match(line) {
let cap = cpy_reg.captures(line).unwrap();
let src = to_register_index(cap.at(1).unwrap());
let dest = to_register_index(cap.at(2).unwrap());
registers[dest] = registers[src];
}
else if inc.is_match(line) {
let cap = inc.captures(line).unwrap();
let dest = to_register_index(cap.at(1).unwrap());
registers[dest] = registers[dest] + 1;
}
else if dec.is_match(line) {
let cap = dec.captures(line).unwrap();
let dest = to_register_index(cap.at(1).unwrap());
registers[dest] = registers[dest] - 1;
}
else if jnz_lit.is_match(line) {
let cap = jnz_lit.captures(line).unwrap();
let condition: i32 = cap.at(1).unwrap().parse().unwrap();
let offset: i32 = cap.at(2).unwrap().parse().unwrap();
if condition != 0 {
pc_next = (pc as i32 + offset) as usize;
}
}
else if jnz_reg.is_match(line) {
let cap = jnz_reg.captures(line).unwrap();
let condition = to_register_index(cap.at(1).unwrap());
let offset: i32 = cap.at(2).unwrap().parse().unwrap();
if registers[condition] != 0 {
pc_next = (pc as i32 + offset) as usize;
}
}
pc = pc_next;
}
println!("a: {}, b: {}, c: {}, d: {}", registers[0], registers[1], registers[2], registers[3]);
}
fn to_register_index(name: &str) -> usize {
match name {
"a" => 0,
"b" => 1,
"c" => 2,
"d" => 3,
_ => panic!("Invalid register provided")
}
}
fn read_file() -> Vec<String> {
let file = BufReader::new(File::open("input.txt").unwrap());
file.lines()
.map(|line| line.unwrap().trim().to_string())
.filter(|line| line.len() > 0)
.collect()
}
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