4 files changed, 249 insertions, 0 deletions
diff --git a/16/Cargo.toml b/16/Cargo.toml
new file mode 100644
index 0000000..a8b1866
--- /dev/null
+++ b/16/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "advent_16"
+version = "0.1.0"
+authors = ["Irene Knapp <ireneista@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+advent_lib = { path = "../lib" }
+
+[dev-dependencies]
+assert_cmd = "0.10"
diff --git a/16/input b/16/input
new file mode 100644
index 0000000..019f19b
--- /dev/null
+++ b/16/input
@@ -0,0 +1 @@
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
diff --git a/16/src/main.rs b/16/src/main.rs
new file mode 100644
index 0000000..f4f6253
--- /dev/null
+++ b/16/src/main.rs
@@ -0,0 +1,219 @@
+use advent_lib::prelude::*;
+
+#[derive(Debug)]
+struct Packet {
+  version: u8,
+  type_id: u8,
+  content: Vec<u8>,
+  subpackets: Vec<Packet>,
+}
+
+
+fn main() -> Result<()> {
+  let mut args = std::env::args();
+  if args.len() != 2 {
+    eprintln!("Usage: advent input");
+  }
+  let _ = args.next();
+  let filename = args.next().unwrap();
+
+  let input = advent_lib::read_lines_file(&filename)?;
+
+  let mut bit_string: Vec<u8> = Vec::new();
+  for c in input[0].chars() {
+    let value = c.to_digit(16).unwrap() as u8;
+    for i in 0 .. 4 {
+      let bit = (value >> (3 - i)) & 1;
+      bit_string.push(bit);
+    }
+  }
+
+  let mut iter = bit_string.iter().peekable();
+  let (version_total, _top_packet, result) = read_packet(&mut iter).unwrap();
+  println!("{}", version_total);
+  println!("{}", result);
+
+  Ok(())
+}
+
+
+fn read_packet<'a>(iter: &mut impl Iterator<Item=&'a u8>) -> Result<(u64, Packet, u128)>
+{
+  let mut version_total: u64 = 0;
+
+  let version = bits_to_u8(take_bits(iter, 3)?);
+  let type_id = bits_to_u8(take_bits(iter, 3)?);
+
+  version_total += version as u64;
+
+  if type_id == 4 {
+    let mut result = 0;
+    loop {
+      let bits = take_bits(iter, 5)?;
+
+      let bits_value = bits_to_u128(bits[1..].to_vec());
+      result = result << 4;
+      result += bits_value;
+
+      if bits[0] == 0 {
+        break;
+      }
+    }
+
+    Ok((version_total, Packet {
+      version,
+      type_id,
+      content: Vec::new(),
+      subpackets: Vec::new(),
+    }, result))
+  } else {
+    let mut subpackets = Vec::new();
+    let mut parameters = Vec::new();
+
+    let length_type_id = bits_to_u8(take_bits(iter, 1)?);
+    if length_type_id == 0 {
+      let length_in_bits = bits_to_u64(take_bits(iter, 15)?);
+
+      let mut content_bits: Vec<u8> = Vec::new();
+      for bit in iter.take(length_in_bits as usize) {
+        content_bits.push(*bit);
+      }
+
+      let mut content_bits = content_bits.iter().peekable();
+
+      loop {
+        match read_packet(&mut content_bits) {
+          Err(_) => {
+            break;
+          }
+          Ok((sub_version_total, subpacket, value)) => {
+            version_total += sub_version_total;
+            subpackets.push(subpacket);
+            parameters.push(value);
+          }
+        }
+      }
+    } else {
+      let n_subpackets = bits_to_u64(take_bits(iter, 11)?);
+
+      for _ in 0 .. n_subpackets {
+        match read_packet(iter) {
+          Err(_) => {
+            return Err(advent_lib::error::Error::Unspecified);
+          }
+          Ok((sub_version_total, subpacket, value)) => {
+            version_total += sub_version_total;
+            subpackets.push(subpacket);
+            parameters.push(value);
+          }
+        }
+      }
+    }
+
+    let mut result = 0;
+    match type_id {
+      0 => {
+        result = 0;
+        for parameter in &parameters {
+          result += parameter;
+        }
+      }
+      1 => {
+        result = 1;
+        for parameter in &parameters {
+          result *= parameter;
+        }
+      }
+      2 => {
+        result = parameters[0];
+        for parameter in &parameters {
+          if *parameter < result {
+            result = *parameter;
+          }
+        }
+      }
+      3 => {
+        result = parameters[0];
+        for parameter in &parameters {
+          if *parameter > result {
+            result = *parameter;
+          }
+        }
+      }
+      5 => {
+        result = if parameters[0] > parameters[1] { 1 } else { 0 };
+      }
+      6 => {
+        result = if parameters[0] < parameters[1] { 1 } else { 0 };
+      }
+      7 => {
+        result = if parameters[0] == parameters[1] { 1 } else { 0 };
+      }
+      _ => { }
+    }
+
+    Ok((version_total, Packet {
+      version,
+      type_id,
+      content: Vec::new(),
+      subpackets: subpackets,
+    }, result))
+  }
+}
+
+
+fn take_bits<'a>(iter: &mut impl Iterator<Item=&'a u8>, count: usize)
+  -> Result<Vec<u8>>
+{
+  let mut result: Vec<u8> = Vec::new();
+
+  for _ in 0 .. count {
+    match iter.next() {
+      None => {
+        return Err(advent_lib::error::Error::Unspecified);
+      }
+      Some(bit) => {
+        result.push(*bit);
+      }
+    }
+  }
+
+  Ok(result)
+}
+
+
+fn bits_to_u8(bits: Vec<u8>) -> u8 {
+  let mut result = 0;
+
+  for bit in &bits {
+    result *= 2;
+    result += bit;
+  }
+
+  result
+}
+
+
+fn bits_to_u64(bits: Vec<u8>) -> u64 {
+  let mut result = 0;
+
+  for bit in &bits {
+    result *= 2;
+    result += *bit as u64;
+  }
+
+  result
+}
+
+
+fn bits_to_u128(bits: Vec<u8>) -> u128 {
+  let mut result = 0;
+
+  for bit in &bits {
+    result *= 2;
+    result += *bit as u128;
+  }
+
+  result
+}
+
diff --git a/16/tests/main.rs b/16/tests/main.rs
new file mode 100644
index 0000000..ba7a189
--- /dev/null
+++ b/16/tests/main.rs
@@ -0,0 +1,18 @@
+use assert_cmd::prelude::*;
+//use predicates::prelude::*;
+use std::process::Command;
+
+
+#[test]
+fn personal_input() -> Result<(), Box<dyn std::error::Error>> {
+  let mut command = Command::cargo_bin("advent_16")?;
+
+  command.arg("input");
+  command.assert().success().stdout(
+      "989\n\
+      7936430475134\n");
+
+
+  Ok(())
+}
+