WIP: day-16: Implement part 2

day-16/Cargo.lock

@@ -14,10 +14,17 @@ name = "day-16"
 version = "0.1.0"
 dependencies = [
  "indoc",
+ "itertools",
  "lazy_static",
  "regex",
 ]
 
+[[package]]
+name = "either"
+version = "1.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
+
 [[package]]
 name = "indoc"
 version = "0.3.6"
@@ -41,6 +48,15 @@ dependencies = [
  "unindent",
 ]
 
+[[package]]
+name = "itertools"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "284f18f85651fe11e8a991b2adb42cb078325c996ed026d994719efcfca1d54b"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.4.0"

day-16/Cargo.toml

@@ -8,5 +8,6 @@ edition = "2018"
 
 [dependencies]
 indoc = "0.3"
+itertools = "0.9"
 lazy_static = "1.4"
 regex = "1.4"

day-16/src/main.rs

@@ -2,6 +2,7 @@ use std::collections::HashMap;
 use std::fs;
 use std::ops::RangeInclusive;
 
+use itertools::Itertools;
 use lazy_static::lazy_static;
 use regex::Regex;
 
@@ -10,13 +11,29 @@ type Ticket = Vec<u32>;
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let input = fs::read_to_string("input")?;
-    let (rules, _, tickets) = parse_tickets(&input)?;
+    let (rules, own_ticket, tickets) = parse_tickets(&input)?;
 
     // Part 1
     let invalid = get_invalid_values(&rules, &tickets);
-
     println!("{}", invalid.iter().sum::<u32>());
 
+    // Part 2
+    let valid = get_valid_tickets(&rules, &tickets);
+    let order = get_value_order(&rules, &valid);
+
+    let result: u32 = order
+        .iter()
+        .zip(own_ticket)
+        .filter_map(|(name, value)| {
+            if name.starts_with("departure") {
+                Some(value)
+            } else {
+                None
+            }
+        })
+        .product();
+    println!("{}", result);
+
     Ok(())
 }
 
@@ -84,6 +101,68 @@ fn get_invalid_values(rules: &Rules, tickets: &Vec<Ticket>) -> Vec<u32> {
         .collect()
 }
 
+fn get_valid_tickets(rules: &Rules, tickets: &Vec<Ticket>) -> Vec<Ticket> {
+    tickets
+        .iter()
+        .filter(|ticket| {
+            ticket.iter().all(|value| {
+                rules
+                    .values()
+                    .any(|(rule1, rule2)| rule1.contains(value) || rule2.contains(value))
+            })
+        })
+        .cloned()
+        .collect()
+}
+
+fn get_value_order(rules: &Rules, tickets: &Vec<Ticket>) -> Vec<String> {
+    let rules: Vec<(String, (RangeInclusive<u32>, RangeInclusive<u32>))> = rules
+        .iter()
+        .map(|tup| (tup.0.clone(), (tup.1 .0, tup.1 .1)))
+        .collect();
+    rules.sort_by(|name, (_, (rule1, rule2))| rule1.count() + rule2.count());
+
+    let mut next_ticket = 0;
+    let mut order: Vec<String> = rules.keys().cloned().collect();
+    let order_fits = |order: &Vec<String>, ticket: &Ticket| {
+        order.iter().zip(ticket).all(|(name, value)| {
+            let (rule1, rule2) = rules.get(name).expect("Must be there");
+            rule1.contains(value) || rule2.contains(value)
+        })
+    };
+
+    loop {
+        if order_fits(&order, &tickets[next_ticket]) {}
+    }
+
+    // rules
+    //     .iter()
+    //     .permutations(rules.len())
+    //     .filter_map(|rules| {
+    //         if tickets.iter().all(|ticket| {
+    //             rules
+    //                 .iter()
+    //                 .zip(ticket)
+    //                 .all(|((_, (rule1, rule2)), value)| {
+    //                     rule1.contains(value) | rule2.contains(value)
+    //                 })
+    //         }) {
+    //             Some(
+    //                 rules
+    //                     .iter()
+    //                     .map(|rule| rule.0.clone())
+    //                     .collect::<Vec<String>>(),
+    //             )
+    //         } else {
+    //             None
+    //         }
+    //     })
+    //     .next()
+    //     .expect("Must have a valid solution")
+
+    unimplemented!()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -115,4 +194,31 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn test_simple2() -> Result<(), Box<dyn std::error::Error>> {
+        let input = indoc!(
+            "
+             class: 0-1 or 4-19
+             row: 0-5 or 8-19
+             seat: 0-13 or 16-19
+
+             your ticket:
+             11,12,13
+
+             nearby tickets:
+             3,9,18
+             15,1,5
+             5,14,9
+            "
+        );
+
+        let (rules, _, tickets) = parse_tickets(input)?;
+        let valid = get_valid_tickets(&rules, &tickets);
+        let order = get_value_order(&rules, &valid);
+
+        assert_eq!(order, vec!["row", "class", "seat"]);
+
+        Ok(())
+    }
 }