From dd5fafc242b9bf862213b89cd0c2b4aed1913078 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tristan=20Dani=C3=ABl=20Maat?= <tm@tlater.net>
Date: Wed, 16 Dec 2020 18:15:33 +0000
Subject: [PATCH] Implement part 1

---
 day-16/Cargo.lock  | 50 +++++++++++++++++++++++++++++
 day-16/Cargo.toml  |  2 ++
 day-16/src/main.rs | 80 +++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 124 insertions(+), 8 deletions(-)

diff --git a/day-16/Cargo.lock b/day-16/Cargo.lock
index 202b749..e48194d 100644
--- a/day-16/Cargo.lock
+++ b/day-16/Cargo.lock
@@ -1,10 +1,21 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
+[[package]]
+name = "aho-corasick"
+version = "0.7.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7404febffaa47dac81aa44dba71523c9d069b1bdc50a77db41195149e17f68e5"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "day-16"
 version = "0.1.0"
 dependencies = [
  "indoc",
+ "lazy_static",
+ "regex",
 ]
 
 [[package]]
@@ -30,6 +41,18 @@ dependencies = [
  "unindent",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "memchr"
+version = "2.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ee1c47aaa256ecabcaea351eae4a9b01ef39ed810004e298d2511ed284b1525"
+
 [[package]]
 name = "proc-macro-hack"
 version = "0.5.19"
@@ -54,6 +77,24 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "regex"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "38cf2c13ed4745de91a5eb834e11c00bcc3709e773173b2ce4c56c9fbde04b9c"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+ "thread_local",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3b181ba2dcf07aaccad5448e8ead58db5b742cf85dfe035e2227f137a539a189"
+
 [[package]]
 name = "syn"
 version = "1.0.54"
@@ -65,6 +106,15 @@ dependencies = [
  "unicode-xid",
 ]
 
+[[package]]
+name = "thread_local"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d40c6d1b69745a6ec6fb1ca717914848da4b44ae29d9b3080cbee91d72a69b14"
+dependencies = [
+ "lazy_static",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.1"
diff --git a/day-16/Cargo.toml b/day-16/Cargo.toml
index beeff78..9599ebe 100644
--- a/day-16/Cargo.toml
+++ b/day-16/Cargo.toml
@@ -8,3 +8,5 @@ edition = "2018"
 
 [dependencies]
 indoc = "0.3"
+lazy_static = "1.4"
+regex = "1.4"
diff --git a/day-16/src/main.rs b/day-16/src/main.rs
index bc8bdb9..9d9fd7a 100644
--- a/day-16/src/main.rs
+++ b/day-16/src/main.rs
@@ -1,23 +1,87 @@
+use std::collections::HashMap;
 use std::fs;
+use std::ops::RangeInclusive;
+
+use lazy_static::lazy_static;
+use regex::Regex;
+
+type Rules = HashMap<String, (RangeInclusive<u32>, RangeInclusive<u32>)>;
+type Ticket = Vec<u32>;
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let input = fs::read_to_string("input")?;
-    let (_, tickets) = parse_tickets(&input)?;
+    let (rules, _, tickets) = parse_tickets(&input)?;
 
     // Part 1
-    let invalid = get_invalid_values(&tickets);
+    let invalid = get_invalid_values(&rules, &tickets);
 
     println!("{}", invalid.iter().sum::<u32>());
 
     Ok(())
 }
 
-fn parse_tickets(input: &str) -> Result<(Vec<u32>, Vec<Vec<u32>>), &str> {
-    unimplemented!()
+fn parse_tickets(input: &str) -> Result<(Rules, Ticket, Vec<Ticket>), String> {
+    let blocks: Vec<&str> = input.split("\n\n").collect();
+    let parse_u32 = |val: &str| {
+        val.parse::<u32>()
+            .map_err(|e| format!("Invalid number: {}", e))
+    };
+
+    if blocks.len() < 3 {
+        Err("Input incomplete")?;
+    }
+
+    let rules = blocks[0]
+        .lines()
+        .map(|line| {
+            lazy_static! {
+                static ref RULE_RE: Regex =
+                    Regex::new(r"([[:alpha:]]+?): (\d+)-(\d+) or (\d+)-(\d+)")
+                        .expect("Regex should compile");
+            }
+
+            let caps = RULE_RE
+                .captures(line)
+                .ok_or(format!("Invalid rule line: {}", line))?;
+
+            let name = caps[1].to_string();
+            let range1 = parse_u32(&caps[2])?..=parse_u32(&caps[3])?;
+            let range2 = parse_u32(&caps[4])?..=parse_u32(&caps[5])?;
+
+            Ok((name, (range1, range2)))
+        })
+        .collect::<Result<Rules, String>>()?;
+
+    let own_ticket = blocks[1]
+        .lines()
+        .skip(1)
+        .next()
+        .ok_or("Input incomplete")?
+        .split(',')
+        .map(|c| parse_u32(c))
+        .collect::<Result<Ticket, String>>()?;
+
+    let other_tickets = blocks[2]
+        .lines()
+        .skip(1)
+        .map(|line| line.split(',').map(|c| parse_u32(c)).collect())
+        .collect::<Result<Vec<Ticket>, String>>()?;
+
+    Ok((rules, own_ticket, other_tickets))
 }
 
-fn get_invalid_values(tickets: &Vec<Vec<u32>>) -> Vec<u32> {
-    unimplemented!()
+fn get_invalid_values(rules: &Rules, tickets: &Vec<Ticket>) -> Vec<u32> {
+    tickets
+        .iter()
+        .flat_map(|ticket| {
+            ticket.iter().filter(|value| {
+                !rules
+                    .values()
+                    .any(|(rule1, rule2)| rule1.contains(value) || rule2.contains(value))
+            })
+        })
+        .copied()
+        .collect()
 }
 
 #[cfg(test)]
@@ -44,8 +108,8 @@ mod tests {
             "
         );
 
-        let (_, tickets) = parse_tickets(input)?;
-        let invalid = get_invalid_values(&tickets);
+        let (rules, _, tickets) = parse_tickets(input)?;
+        let invalid = get_invalid_values(&rules, &tickets);
 
         assert_eq!(invalid.iter().sum::<u32>(), 71);