Holy crap rust

2021/readme.md

@@ -11,9 +11,7 @@ Specifically, here's my `deno --version` output:
     v8 9.7.106.5
     typescript 4.4.2
 
-Enjoy!
-
-**EDIT**: Since performance is not what I would like, it looks like I'm also doing some of these in Nim.
+It looks like I'm also doing some of these in Nim.
 
     $ nim --version
     Nim Compiler Version 1.6.0 [Linux: amd64]
@@ -23,9 +21,16 @@ Enjoy!
     git hash: 727c6378d2464090564dbcd9bc8b9ac648467e38
     active boot switches: -d:release
 
+And I decided part way through to do some Rust.
+
+    $ rustc --version
+    rustc 1.58.0-beta.2 (0e07bcb68 2021-12-04)
+
+Enjoy!
+
 ## Usage
 
-Run these solutions like so:
+Run these solutions like so from their respective directories:
 
     deno run --unstable --allow-all $DAY.ts
 
@@ -33,6 +38,10 @@ And the Nim ones like so:
 
     nim c -d:release -d:ssl --run day$DAY.nim
 
+And Rust:
+
+    rustc -O --out-dir build day$DAY.rs && ./build/day$DAY
+
 And if you want to measure memory usage with Deno programs:
 
     mkdir -p build
@@ -45,23 +54,28 @@ Or for Nim programs:
     nim c -d:release -d:ssl --outdir:build day$DAY.nim
     /usr/bin/time -v ./day$DAY
 
+And similarly for Rust:
+
+    rustc -O --out-dir build day$DAY.rs
+    /usr/bin/time -v ./build/day$DAY
+
 # Days
 
-- [x] Day 1: [Deno](./1.ts), [Nim](./one.nim)
-- [x] Day 2: [Deno](./2.ts), [Nim](./two.nim)
-- [x] Day 3: [Deno](./3.ts), [Nim](./three.nim)
-- [x] Day 4: [Nim](./four.nim)
-- [x] Day 5: [Nim](./five.nim)
-- [x] Day 6: [Nim](./six.nim)
-- [x] Day 7: [Nim](./seven.nim)
-- [x] Day 8: [Nim](./eight.nim)
-- [ ] Day 9
-- [ ] Day 10
-- [ ] Day 11
-- [ ] Day 12
-- [ ] Day 13
-- [ ] Day 14
-- [ ] Day 15
+- [x] Day 1: [Deno](./deno/1.ts), [Nim](./nim/day1.nim)
+- [x] Day 2: [Deno](./deno/2.ts), [Nim](./nim/day2.nim)
+- [x] Day 3: [Deno](./deno/3.ts), [Nim](./nim/day3.nim)
+- [x] Day 4: [Nim](./nim/day4.nim)
+- [x] Day 5: [Nim](./nim/day5.nim)
+- [x] Day 6: [Nim](./nim/day6.nim)
+- [x] Day 7: [Nim](./nim/day7.nim)
+- [x] Day 8: [Nim](./nim/day8.nim)
+- [x] Day 9: [Nim](./nim/day9.nim)
+- [x] Day 10: [Nim](./nim/day10.nim)
+- [x] Day 11: [Nim](./nim/day11.nim)
+- [x] Day 12: [Nim](./nim/day12.nim)
+- [x] Day 13: [Nim](./nim/day13.nim)
+- [x] Day 14: [Nim](./nim/day14.nim)
+- [x] Day 15: [Nim](./nim/day15.nim)
 - [ ] Day 16
 - [ ] Day 17
 - [ ] Day 18

2021/rust/.gitignore

@@ -0,0 +1 @@
+/target

2021/rust/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc2021"
+version = "0.1.0"

2021/rust/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "aoc2021"
+version = "0.1.0"
+edition = "2021"
+include = ["common.rs"]
+
+[[bin]]
+name = "day16"
+path = "day16.rs"
+
+[dependencies]

2021/rust/common.rs

@@ -0,0 +1,25 @@
+use std::env::var as envvar;
+use std::path::Path;
+use std::fs;
+
+const ASCII_UPPER_A: u8 = 65;
+const ASCII_LOWER_A: u8 = 97;
+const ASCII_0: u8 = 48;
+
+pub fn day_input(day: u8) -> String {
+    let home = &envvar("HOME").unwrap();
+    let home_path = Path::new(home);
+    let path_buf = home_path.join(format!("./.cache/aoc2021/{0}.input", day));
+    let file_path = path_buf.to_str().unwrap();
+    fs::read_to_string(file_path).unwrap()
+}
+
+pub const fn hex_val(c: char) -> Result<u8, &'static str> {
+    match c {
+        'A'..='F' => Ok(c as u8 - ASCII_UPPER_A + 10),
+        'a'..='f' => Ok(c as u8 - ASCII_LOWER_A + 10),
+        '0'..='9' => Ok(c as u8 - ASCII_0 as u8),
+        _ => Err("invalid hex char"),
+    }
+}
+

2021/rust/day16.rs

@@ -0,0 +1,251 @@
+#![warn(clippy::all, clippy::pedantic)]
+
+mod common;
+use common::{day_input, hex_val};
+
+/// # Panics
+/// we may panic
+pub fn hex_string_to_bytes(s: &String) -> Vec<u8> {
+    let bytes = s
+        .trim()
+        .chars()
+        .collect::<Vec<char>>()
+        .chunks(2)
+        .enumerate()
+        .map(|(_, ct)| Ok(hex_val(ct[0])? << 4 | hex_val(ct[1])?))
+        .collect::<Result<Vec<u8>, &'static str>>()
+        .unwrap();
+
+    println!("Hex String: {}", s);
+    bytes.iter().for_each(|b| println!("{:#010b}", b));
+    bytes
+}
+
+/// # Errors
+/// lots of them
+/// # Panics
+/// whenever I want
+pub fn parse_bytes_from_bits(bytes: &[u8], bit_offset: usize, length: u8) -> Result<u64, &'static str> {
+    if length > 64 {
+        return Err("cannot parse bytes with length > 64");
+    }
+
+    // first chunk
+    let mut result = 0u64;
+    let start = bit_offset;
+    let end = bit_offset + usize::from(length);
+    let first_offset = start % 8;
+    // println!("Start: {}, End: {}", start, end);
+    let first_chunk_size = if first_offset + usize::from(length) >= 8 { 8 - (start % 8) } else { end - start };
+    let byte_offset = bit_offset / 8;
+    /* println!("{:?}", vec![
+        first_offset,
+        first_chunk_size,
+        (8 - first_chunk_size - first_offset),
+        usize::from(bytes[byte_offset] << first_offset >> first_offset >> (8 - first_chunk_size - first_offset))
+    ]); */
+    result += u64::from(bytes[byte_offset] << first_offset >> first_offset >> (8 - first_chunk_size - first_offset));
+
+    // middle bytes
+    let num_bytes = (first_offset + usize::from(length) + 7) / 8;
+    // println!("Num Bytes: {}, Bit Offset: {}, Length: {}", num_bytes, bit_offset, length);
+    for n in 1..(num_bytes - 1) {
+        result <<= 8;
+        result += u64::from(bytes[byte_offset + n]);
+        // println!("After Mid Byte: {:#066b}", result);
+    }
+    
+    // last chunk
+    if num_bytes > 1 {
+        let bits_so_far = first_chunk_size + ((num_bytes - 2) * 8);
+        let bits_left = usize::from(length) - bits_so_far;
+        // println!("left: {}", bits_left);
+        let cutoff = 8 - bits_left;
+        let last_byte_index = byte_offset + num_bytes - 1;
+        let byte = bytes[last_byte_index];
+        let addend = byte >> cutoff;
+        result <<= bits_left;
+        result += u64::from(addend);
+        // println!("After Last Byte: {:#066b} ({}: {}) {} {:#010b}", result, last_byte_index, byte, cutoff, addend);
+    }
+    println!(" -> BFROMB Result: {:#066b} ({}->{} [{}] across {} bytes)", result, start, end, length, num_bytes);
+    Ok(result)
+}
+
+#[derive(Debug)]
+struct BITSLiteralValue {
+    value: u64
+}
+
+#[derive(Debug)]
+enum BITSLengthType {
+    SubpacketBits,
+    SubpacketCount,
+}
+
+#[derive(Debug)]
+struct BITSOperator {
+    length_type: BITSLengthType,
+    length: u64,
+    subpackets: Vec<BITSPacket>,
+}
+
+#[derive(Debug)]
+enum BITSValue {
+    LiteralValue(BITSLiteralValue),
+    Operator(BITSOperator),
+}
+
+#[derive(Debug)]
+pub struct BITSPacket {
+    version: u8,
+    packet_type: u8,
+    inner: BITSValue,
+}
+
+#[derive(Debug)]
+struct ParsedPacket {
+    bits_parsed: usize,
+    packet: BITSPacket,
+}
+
+fn parse_packet(bytes: &[u8], packet_start_bit: usize) -> Result<ParsedPacket, &'static str> {
+    println!("PARSE PACKET at {}", packet_start_bit);
+    let version = parse_bytes_from_bits(bytes, packet_start_bit, 3)?;
+    let packet_type = parse_bytes_from_bits(bytes, packet_start_bit + 3, 3)?;
+    println!("Processing packet with version {0} of type {2} at bit_index {1}", version, packet_start_bit, packet_type);
+    if packet_type == 4 {
+        let mut bit_index = packet_start_bit + 6;
+        let mut value = 0u64;
+        loop {
+            let value_segment = parse_bytes_from_bits(bytes, bit_index, 5)?;
+            value = (value << 4) & (value_segment & 0b1111);
+            println!("Literal Value Segment at {}...", bit_index);
+            bit_index += 5;
+            if value_segment < 0b10000u64 { break; }
+        }
+        println!("PARSE PACKET DONE (at {})", packet_start_bit);
+        Ok(ParsedPacket {
+            bits_parsed: bit_index - packet_start_bit,
+            packet: BITSPacket {
+                version: version.to_le_bytes()[0],
+                packet_type: packet_type.to_le_bytes()[0],
+                inner: BITSValue::LiteralValue(BITSLiteralValue { value }),
+            }
+        })
+    } else if parse_bytes_from_bits(bytes, packet_start_bit + 6, 1)? == 0u64 {
+        println!("Operator...");
+        let length = parse_bytes_from_bits(bytes, packet_start_bit + 7, 15)?;
+        println!("Length in bits: {}", length);
+        // ignore subpackets parsing in this case
+        // 7 bits for the version, type, and length_type header, 15 bits of length, and
+        // 8 bits to ensure we're on the next packet boundary
+        let mut subpacket_bits = 0usize;
+        let mut subpackets = vec![];
+        while u64::try_from(subpacket_bits).unwrap() < length {
+            let pp = parse_packet(bytes, packet_start_bit + 7 + 15 + subpacket_bits)?;
+            subpacket_bits += pp.bits_parsed;
+            subpackets.push(pp.packet);
+        }
+        println!("PARSE PACKET DONE (at {})", packet_start_bit);
+        Ok(ParsedPacket {
+            bits_parsed: 7 + 15 + subpacket_bits,
+            packet: BITSPacket {
+                version: version.to_le_bytes()[0],
+                packet_type: packet_type.to_le_bytes()[0],
+                inner: BITSValue::Operator(BITSOperator {
+                    length_type: BITSLengthType::SubpacketCount,
+                    length,
+                    subpackets,
+                }),
+            }
+        })
+    } else {
+        println!("Operator...");
+        // 11 bits of length
+        let length = parse_bytes_from_bits(bytes, packet_start_bit + 7, 11)?;
+        println!("Length in subpackets: {}", length);
+        let mut bit_index = packet_start_bit + 7 + 11;
+        let mut subpackets = vec![];
+        for _ in 0..length {
+            let pp = parse_packet(bytes, bit_index)?;
+            bit_index += pp.bits_parsed;
+            subpackets.push(pp.packet);
+        }
+        println!("PARSE PACKET DONE (at {})", packet_start_bit);
+        // 7 bits for the version, type, and length_type header, 11 bits of length, and
+        // 8 bits to ensure we're on the next packet boundary
+        Ok(ParsedPacket {
+            bits_parsed: bit_index - packet_start_bit,
+            packet: BITSPacket {
+                version: version.to_le_bytes()[0],
+                packet_type: packet_type.to_le_bytes()[0],
+                inner: BITSValue::Operator(BITSOperator {
+                    length_type: BITSLengthType::SubpacketBits,
+                    length,
+                    subpackets,
+                }),
+            }
+        })
+    }
+}
+
+/// # Panics
+/// anytime I want
+pub fn packet_version_sum(packet: BITSPacket) -> u64 {
+    // bytes.iter().for_each(|b| println!("{:#010b}", b));
+    if let BITSValue::Operator(p) = packet.inner {
+        let mut result = 0u64;
+        for p in p.subpackets {
+            result += packet_version_sum(p);
+        }
+        result + u64::from(packet.version)
+    } else {
+        u64::from(packet.version)
+    }
+}
+
+fn main() {
+    let bytes = hex_string_to_bytes(&day_input(16));
+    bytes.iter().for_each(|b| println!("{:#010b}", b));
+    let packet = parse_packet(&bytes, 0).unwrap().packet;
+    // println!("{:#?}", packet);
+    let version_sum = packet_version_sum(packet);
+    println!("Sum of packet versions: {:?}", version_sum);
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn packet_version_sum_examples() {
+        let tester = |s: &str| packet_version_sum(parse_packet(&hex_string_to_bytes(&s.to_string()), 0).unwrap().packet);
+        assert_eq!(tester("8A004A801A8002F478"), 16);
+        assert_eq!(tester("620080001611562C8802118E34"), 12);
+        assert_eq!(tester("C0015000016115A2E0802F182340"), 23);
+        assert_eq!(tester("A0016C880162017C3686B18A3D4780"), 31);
+    }
+
+    #[test]
+    fn parse_bytes_from_bits_examples() {
+        let v: Vec<u8> = vec![0b0011_0011, 0b0100_1111, 0b1101_1011, 0b1001_1010];
+        // assert_eq!(0b1100_1011u8 >> 9u8, 0b0);
+        // assert_eq!(0b1100_1011u8 >> 8u8, 0b0);
+        assert_eq!(0b1100_1011u8 >> 7u8, 0b1);
+        assert_eq!(parse_bytes_from_bits(&v, 2, 1), Ok(0b1));
+        assert_eq!(parse_bytes_from_bits(&v, 2, 2), Ok(0b11));
+        assert_eq!(parse_bytes_from_bits(&v, 1, 2), Ok(0b01));
+        assert_eq!(parse_bytes_from_bits(&v, 0, 3), Ok(0b001));
+        assert_eq!(parse_bytes_from_bits(&v, 0, 8), Ok(0b0011_0011u64));
+        assert_eq!(parse_bytes_from_bits(&v, 2, 8), Ok(0b1100_1101u64));
+        assert_eq!(parse_bytes_from_bits(&v, 6, 8), Ok(0b1101_0011u64));
+        assert_eq!(parse_bytes_from_bits(&v, 7, 10), Ok(0b10_1001_1111u64));
+        assert_eq!(parse_bytes_from_bits(&v, 7, 3), Ok(0b101u64));
+        assert_eq!(parse_bytes_from_bits(&v, 6, 3), Ok(0b110u64));
+        assert_eq!(parse_bytes_from_bits(&v, 22, 3), Ok(0b111u64));
+        assert_eq!(parse_bytes_from_bits(&v, 7, 20), Ok(0b1010_0111_1110_1101_1100u64));
+        assert_eq!(parse_bytes_from_bits(&v, 15, 12), Ok(0b1110_1101_1100u64));
+        assert_eq!(parse_bytes_from_bits(&v, 18, 3), Ok(0b011u64));
+    }
+}

2021/rust/main.rs

@@ -0,0 +1 @@
+// empty since all the source actually lives in each day