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aoc2021
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Improved Day 16 Part 1 by replacing strings with bitvec

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master 16.1b
Ishan Jain 1 year ago
parent 2f11a57ec2
commit f97789eac6
4 changed files with 170 additions and 149 deletions
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49
Cargo.lock generated
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@ -5,3 +5,52 @@ version = 3
[[package]]
name = "aoc2021"
version = "0.1.0"
dependencies = [
"bitvec",
"hex",
]
[[package]]
name = "bitvec"
version = "0.22.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "5237f00a8c86130a0cc317830e558b966dd7850d48a953d998c813f01a41b527"
dependencies = [
"funty",
"radium",
"tap",
"wyz",
]
[[package]]
name = "funty"
version = "1.2.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "1847abb9cb65d566acd5942e94aea9c8f547ad02c98e1649326fc0e8910b8b1e"
[[package]]
name = "hex"
version = "0.4.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
[[package]]
name = "radium"
version = "0.6.2"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "643f8f41a8ebc4c5dc4515c82bb8abd397b527fc20fd681b7c011c2aee5d44fb"
[[package]]
name = "tap"
version = "1.0.1"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "55937e1799185b12863d447f42597ed69d9928686b8d88a1df17376a097d8369"
[[package]]
name = "wyz"
version = "0.4.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "129e027ad65ce1453680623c3fb5163cbf7107bfe1aa32257e7d0e63f9ced188"
dependencies = [
"tap",
]

2
Cargo.toml
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@ -6,6 +6,8 @@ edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
bitvec = "0.22.3"
hex = "0.4.3"
[profile.release]

2
inputs/sample.txt
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@ -1 +1 @@
9C0141080250320F1802104A08
A0016C880162017C3686B18A3D4780

266
src/main.rs
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@ -1,72 +1,16 @@
#![feature(test)]
use std::collections::HashMap;
extern crate test;
use bitvec::view::BitView;
type BitSlice<'a> = &'a bitvec::slice::BitSlice<bitvec::order::Msb0, u8>;
const INPUTS: [&'static str; 2] = [
include_str!("../inputs/sample.txt"),
include_str!("../inputs/input.txt"),
];
fn parse_input(input: &'static str) -> String {
let mapping = HashMap::from([
('0', "0000"),
('1', "0001"),
('2', "0010"),
('3', "0011"),
('4', "0100"),
('5', "0101"),
('6', "0110"),
('7', "0111"),
('8', "1000"),
('9', "1001"),
('A', "1010"),
('B', "1011"),
('C', "1100"),
('D', "1101"),
('E', "1110"),
('F', "1111"),
]);
let input = input.trim();
let mut out = String::with_capacity(input.len() * 4);
for c in input.chars() {
let v = *mapping.get(&c).unwrap();
out.push_str(v);
}
out
}
fn read_header(s: &mut impl Iterator<Item = char>) -> (u8, u8) {
let raw_version: String = s.by_ref().take(3).collect();
let version = u8::from_str_radix(&raw_version, 2).unwrap();
let raw_type_id: String = s.take(3).collect();
let type_id = u8::from_str_radix(&raw_type_id, 2).unwrap();
(version, type_id)
}
fn read_literal(input: &mut impl Iterator<Item = char>) -> (u64, u64) {
let mut out = String::new();
let mut read = 0;
loop {
let last = input.next().unwrap() == '0';
out.extend(input.take(4));
read += 5;
if last {
break;
}
}
(u64::from_str_radix(&out, 2).unwrap(), read)
}
#[derive(Debug)]
struct PacketHeader {
version: u8,
type_id: u8,
@ -77,121 +21,148 @@ struct Packet {
header: PacketHeader,
size: u64,
literal: Option<u64>,
sub_packets: Vec<Packet>,
}
impl Packet {
fn value(&self) -> u64 {
match self.header.type_id {
0 => self.sub_packets.iter().fold(0, |a, x| a + x.value()),
1 => self.sub_packets.iter().fold(1, |a, x| a * x.value()),
2 => self.sub_packets.iter().map(|x| x.value()).min().unwrap(),
3 => self.sub_packets.iter().map(|x| x.value()).max().unwrap(),
4 => self.literal.unwrap(),
5 => {
let value1 = self.sub_packets[0].value();
let value2 = self.sub_packets[1].value();
if value1 > value2 {
1
} else {
0
}
}
6 => {
let value1 = self.sub_packets[0].value();
let value2 = self.sub_packets[1].value();
if value1 < value2 {
1
} else {
0
}
}
7 => {
let value1 = self.sub_packets[0].value();
let value2 = self.sub_packets[1].value();
if value1 == value2 {
1
} else {
0
}
fn new(input: &'static str) -> Self {
let out = hex::decode(input).unwrap();
let mut bvec: BitSlice = BitView::view_bits(out.as_slice());
Self::parse(&mut bvec)
}
fn read_literal(ip: &mut BitSlice) -> (u64, u64) {
let mut out = 0;
let mut read = 0;
loop {
let (word, remaining) = ip.split_at(5);
*ip = remaining;
read += 5;
out = out << 4 | read_as_u8(&word[1..]) as u64;
if !*word.first().unwrap() {
break;
}
_ => unreachable!(),
}
(out, read)
}
}
fn read_packet(input: &mut impl Iterator<Item = char>) -> Packet {
let (version, type_id) = read_header(input);
fn read_header(ip: &mut BitSlice) -> (u8, u8) {
(take_u8(ip, 3), take_u8(ip, 3))
}
let mut out = Packet {
size: 6,
literal: None,
header: PacketHeader { version, type_id },
sub_packets: vec![],
};
fn parse(input: &mut BitSlice) -> Packet {
let (version, type_id) = Self::read_header(input);
match type_id {
// Literal
4 => {
let (literal, read) = read_literal(input);
let mut out = Packet {
size: 6,
literal: None,
header: PacketHeader { version, type_id },
sub_packets: vec![],
};
out.size += read;
out.literal = Some(literal);
}
match type_id {
// Literal
4 => {
let (literal, read) = Self::read_literal(input);
// Operation
_ => {
let length_type_id = input.next().unwrap();
out.size += 1;
out.size += read;
out.literal = Some(literal);
}
// Operation
_ => {
let length_type_id = take_u8(input, 1);
out.size += 1;
match length_type_id {
'0' => {
let mut trailing_packet_size =
u64::from_str_radix(&input.take(15).collect::<String>(), 2).unwrap();
out.size += 15;
match length_type_id {
0 => {
let mut trailing_packet_size = take_u64(input, 15);
out.size += 15;
while trailing_packet_size > 0 {
let packet = read_packet(input);
while trailing_packet_size > 0 {
let packet = Self::parse(input);
trailing_packet_size -= packet.size;
out.size += packet.size;
out.sub_packets.push(packet);
trailing_packet_size -= packet.size;
out.size += packet.size;
out.sub_packets.push(packet);
}
}
}
'1' => {
let trailing_packet_count =
usize::from_str_radix(&input.take(11).collect::<String>(), 2).unwrap();
out.size += 11;
1 => {
let trailing_packet_count = take_u64(input, 11);
out.size += 11;
for _ in 0..trailing_packet_count {
let packet = read_packet(input);
out.size += packet.size;
out.sub_packets.push(packet);
for _ in 0..trailing_packet_count {
let packet = Self::parse(input);
out.size += packet.size;
out.sub_packets.push(packet);
}
}
_ => unreachable!(),
}
_ => unreachable!(),
}
}
};
};
out
}
}
fn take_u8(ip: &mut BitSlice, offset: usize) -> u8 {
let (num, left) = ip.split_at(offset);
*ip = left;
read_as_u8(num)
}
fn take_u64(ip: &mut BitSlice, offset: usize) -> u64 {
let (num, left) = ip.split_at(offset);
*ip = left;
read_as_u64(num)
}
fn read_as_u64(ip: BitSlice) -> u64 {
let mut out = 0;
for bit in ip {
out = out << 1 | if *bit { 1 } else { 0 };
}
out
}
fn solution(input: String) -> u64 {
let mut input = input.chars();
let packet = read_packet(&mut input);
fn read_as_u8(ip: BitSlice) -> u8 {
let mut out = 0;
for bit in ip {
out = out << 1 | if *bit { 1 } else { 0 };
}
out
}
fn solution(input: &'static str) -> u64 {
let packet = Packet::new(input.trim());
let mut stack = vec![packet];
let mut answer = 0;
while let Some(packet) = stack.pop() {
answer += packet.header.version as u64;
stack.extend(packet.sub_packets);
}
packet.value()
answer
}
fn main() {
for input in INPUTS {
let input = parse_input(input);
let result = solution(input);
println!("Result = {}", result);
}
@ -199,9 +170,8 @@ fn main() {
#[bench]
fn solution_bench(b: &mut test::Bencher) {
let input = parse_input(INPUTS[1]);
b.iter(|| {
let result = solution(input.clone());
let result = solution(INPUTS[1]);
test::black_box(result);
})
}

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