2021: day16: part 1: parse litterals

Cargo.lock

@@ -88,6 +88,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "aoc",
+ "bitvec 0.22.3",
  "rand",
 ]
 
@@ -130,14 +131,26 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
 [[package]]
 name = "bitvec"
-version = "0.19.6"
+version = "0.19.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "55f93d0ef3363c364d5976646a38f04cf67cfe1d4c8d160cdea02cab2c116b33"
+checksum = "a7ba35e9565969edb811639dbebfe34edc0368e472c5018474c8eb2543397f81"
 dependencies = [
  "funty",
- "radium",
+ "radium 0.5.3",
  "tap",
- "wyz",
+ "wyz 0.2.0",
+]
+
+[[package]]
+name = "bitvec"
+version = "0.22.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5237f00a8c86130a0cc317830e558b966dd7850d48a953d998c813f01a41b527"
+dependencies = [
+ "funty",
+ "radium 0.6.2",
+ "tap",
+ "wyz 0.4.0",
 ]
 
 [[package]]
@@ -336,9 +349,9 @@ checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
 
 [[package]]
 name = "funty"
-version = "1.1.0"
+version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fed34cd105917e91daa4da6b3728c47b068749d6a62c59811f06ed2ac71d9da7"
+checksum = "1847abb9cb65d566acd5942e94aea9c8f547ad02c98e1649326fc0e8910b8b1e"
 
 [[package]]
 name = "generic-array"
@@ -470,12 +483,11 @@ dependencies = [
 
 [[package]]
 name = "nom"
-version = "6.2.1"
+version = "6.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c5c51b9083a3c620fa67a2a635d1ce7d95b897e957d6b28ff9a5da960a103a6"
+checksum = "3d521ee2250f619dd5e06515ba405858d249edc8fae9ddee2dba0695e57db01b"
 dependencies = [
- "bitvec",
+ "bitvec 0.19.4",
- "funty",
  "lexical-core",
  "memchr",
  "version_check",
@@ -570,6 +582,12 @@ version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "941ba9d78d8e2f7ce474c015eea4d9c6d25b6a3327f9832ee29a4de27f91bbb8"
 
+[[package]]
+name = "radium"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "643f8f41a8ebc4c5dc4515c82bb8abd397b527fc20fd681b7c011c2aee5d44fb"
+
 [[package]]
 name = "rand"
 version = "0.8.4"
@@ -913,3 +931,12 @@ name = "wyz"
 version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "85e60b0d1b5f99db2556934e21937020776a5d31520bf169e851ac44e6420214"
+
+[[package]]
+name = "wyz"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "129e027ad65ce1453680623c3fb5163cbf7107bfe1aa32257e7d0e63f9ced188"
+dependencies = [
+ "tap",
+]

aoc2021/Cargo.toml

@@ -10,6 +10,7 @@ edition = "2021"
 aoc = { path = "../aoc" }
 anyhow = "1.0"
 rand = "0.8"
+bitvec = "0.22"
 
 [lib]
 path = "src/lib.rs"

aoc2021/input/day16.txt

@@ -0,0 +1 @@
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

aoc2021/src/day16.rs

@@ -0,0 +1,129 @@
+use std::fmt::Write;
+
+use anyhow::{Context, Result};
+use bitvec::prelude::*;
+
+const INPUT: &str = include_str!("../input/day16.txt");
+
+pub fn run() -> Result<String> {
+    let mut res = String::with_capacity(128);
+
+    writeln!(res, "part 1: {}", part1(INPUT)?)?;
+
+    Ok(res)
+}
+
+fn part1(input: &str) -> Result<u64> {
+    let packet: Packet = input.parse()?;
+
+    Ok(packet.version_sum())
+}
+
+#[derive(PartialEq, Eq, Debug)]
+enum PacketType {
+    Litteral(LitteralPacket),
+    Operator(OperatorPacket),
+}
+
+#[derive(PartialEq, Eq, Debug)]
+struct Packet {
+    version: u8,
+    type_id: u8,
+    packet: PacketType,
+}
+
+impl Packet {
+    fn version_sum(&self) -> u64 {
+        match &self.packet {
+            PacketType::Litteral(_) => self.version as u64,
+            PacketType::Operator(op) => op.sub_packets.iter().map(Packet::version_sum).sum(),
+        }
+    }
+}
+
+#[derive(PartialEq, Eq, Debug)]
+struct LitteralPacket {
+    value: u64,
+}
+
+#[derive(PartialEq, Eq, Debug)]
+struct OperatorPacket {
+    sub_packets: Vec<Packet>,
+}
+
+impl std::str::FromStr for Packet {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        let s = s.trim();
+        let mut bits = BitVec::<Msb0, usize>::new();
+        bits.resize(4 * s.len(), false);
+
+        for (i, c) in s.chars().enumerate() {
+            let bit_index = i * 4;
+            let digit = c.to_digit(16).context("character wasn't hex digit")?;
+            bits[bit_index..(bit_index + 4)].store(digit);
+        }
+
+        bits.as_bitslice().try_into()
+    }
+}
+
+impl<'bits, Store> TryFrom<&'bits BitSlice<Msb0, Store>> for Packet
+where
+    Store: BitStore,
+{
+    type Error = anyhow::Error;
+
+    fn try_from(bits: &'bits BitSlice<Msb0, Store>) -> Result<Self> {
+        let version: u8 = bits[0..3].load();
+        let type_id: u8 = bits[3..6].load();
+
+        match type_id {
+            4 => {
+                let mut value = 0;
+                for i in (6..).step_by(5) {
+                    let val = bits[(i + 1)..(i + 5)].load::<u64>();
+                    value = (value << 4) + val;
+
+                    if !bits[i] {
+                        break;
+                    }
+                }
+
+                Ok(Packet {
+                    version,
+                    type_id,
+                    packet: PacketType::Litteral(LitteralPacket { value }),
+                })
+            }
+            _ => unimplemented!("Operator packets aren't implemented yet"),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const PROVIDED1: &str = "D2FE28";
+    const PROVIDED2: &str = "38006F45291200";
+    const PROVIDED3: &str = "EE00D40C823060";
+
+    const PROVIDED4: &str = "8A004A801A8002F478";
+    const PROVIDED5: &str = "620080001611562C8802118E34";
+    const PROVIDED6: &str = "C0015000016115A2E0802F182340";
+    const PROVIDED7: &str = "A0016C880162017C3686B18A3D4780";
+
+    #[test]
+    fn part1_provided() {
+        assert_eq!(
+            PROVIDED1.parse::<Packet>().unwrap(),
+            Packet {
+                version: 6,
+                type_id: 4,
+                packet: PacketType::Litteral(LitteralPacket { value: 2021 }),
+            }
+        );
+    }
+}

aoc2021/src/lib.rs

@@ -15,3 +15,4 @@ pub mod day12;
 pub mod day13;
 pub mod day14;
 pub mod day15;
+pub mod day16;

aoc2021/src/main.rs

@@ -17,6 +17,7 @@ use aoc2021::day12;
 use aoc2021::day13;
 use aoc2021::day14;
 use aoc2021::day15;
+use aoc2021::day16;
 
 fn main() -> Result<()> {
     let days: &[DayFunc] = &[
@@ -35,6 +36,7 @@ fn main() -> Result<()> {
         day13::run,
         day14::run,
         day15::run,
+        day16::run,
     ];
 
     aoc::run(days)