Day 13 part 1

Omg I had the answer ages ago but was counting them instead of adding indexes loooool kill me

2022/rust/src/day13.rs

@@ -0,0 +1,201 @@
+use std::cmp::Ordering;
+use std::str::FromStr;
+
+mod common;
+
+#[derive(Debug, Eq)]
+enum Packet {
+    Num(i32),
+    List(Box<Vec<Packet>>),
+}
+
+#[derive(Debug)]
+enum ParsePacketError {
+    EndOfList,
+    EndOfString,
+}
+
+impl FromStr for Packet {
+    type Err = ParsePacketError;
+
+    fn from_str(orig: &str) -> Result<Self, Self::Err> {
+        println!("orig: {}", orig);
+        match orig.chars().next() {
+            Some('[') => {
+                let contents = &orig[1..orig.len() - 1];
+                let mut chunks = vec![];
+                let mut chunk_start = 0;
+                // this is dumb. I should be able to recurse this crap but my brain must be fried
+                let mut nest_level = 0;
+                for (i, c) in contents.char_indices() {
+                    match c {
+                        '[' => nest_level += 1,
+                        ']' => nest_level -= 1,
+                        ',' => {
+                            if nest_level == 0 {
+                                chunks.push(&contents[chunk_start..i]);
+                                chunk_start = i + 1;
+                            }
+                        }
+                        _ => {}
+                    }
+                }
+                if chunk_start < contents.len() {
+                    chunks.push(&contents[chunk_start..]);
+                }
+                println!("{:?}", chunks);
+                Ok(Self::List(Box::new(
+                    chunks
+                        .iter()
+                        .map(|s| s.parse::<Packet>().unwrap())
+                        .collect(),
+                )))
+            }
+            Some(_) => Ok(Self::Num(orig.parse::<i32>().unwrap())),
+            None => Err(ParsePacketError::EndOfString),
+        }
+    }
+}
+
+impl Ord for Packet {
+    fn cmp(&self, other: &Self) -> Ordering {
+        println!("comparing {:?} with {:?}", self, other);
+        match (self, other) {
+            (Self::Num(l), Self::Num(r)) => l.cmp(r),
+            (Self::List(l), Self::List(r)) => {
+                for (l, r) in std::iter::zip(l.iter(), r.iter()) {
+                    match l.cmp(r) {
+                        Ordering::Equal => continue,
+                        v => {
+                            println!("done: {:?}", v);
+                            return v;
+                        }
+                    }
+                }
+                l.len().cmp(&r.len())
+            }
+            (Self::Num(l), r) => Self::List(Box::new(vec![Self::Num(*l)])).cmp(r),
+            (l, Self::Num(r)) => l.cmp(&Self::List(Box::new(vec![Self::Num(*r)]))),
+        }
+    }
+}
+
+impl PartialOrd for Packet {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl PartialEq for Packet {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Self::Num(l), Self::Num(r)) => l == r,
+            (Self::List(l), Self::List(r)) => {
+                l.len() == r.len() && l.iter().zip(r.iter()).all(|(l, r)| l == r)
+            }
+            (Self::Num(_), Self::List(_)) => false,
+            (Self::List(_), Self::Num(_)) => false,
+        }
+    }
+}
+
+#[derive(Debug)]
+struct PacketPair {
+    left: Packet,
+    right: Packet,
+}
+
+type Input = Vec<PacketPair>;
+type Answer = usize;
+
+fn processed_input(input: &str) -> Input {
+    input
+        .split("\n\n")
+        .map(|c| {
+            let mut l = c.lines();
+            let result = PacketPair {
+                left: l.next().unwrap().parse::<Packet>().unwrap(),
+                right: l.next().unwrap().parse::<Packet>().unwrap(),
+            };
+            println!("{:?}", result);
+            return result;
+        })
+        .collect::<Vec<PacketPair>>()
+}
+
+fn part1(input: &Input) -> Answer {
+    let mut sum = 0;
+    let mut i = 1;
+    for pair in input {
+        if pair.left < pair.right {
+            sum += i
+        }
+        i += 1
+    }
+    sum
+}
+
+fn part2(input: &Input) -> Answer {
+    0
+}
+
+fn main() {
+    let input_text = common::day_input(13);
+    eprintln!("{}\n\nAbove is your input file.\n\n", input_text);
+    let input = processed_input(&input_text);
+    common::show_answers(&part1(&input), &part2(&input))
+    // common::show_both_answers(&both_parts(&input))
+}
+
+// fn both_parts(input: &Input) -> (Answer, Answer) {
+//     (0, 0)
+// }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const TEST_INPUT: &str = "[1,1,3,1,1]
+[1,1,5,1,1]
+
+[[1],[2,3,4]]
+[[1],4]
+
+[9]
+[[8,7,6]]
+
+[[4,4],4,4]
+[[4,4],4,4,4]
+
+[7,7,7,7]
+[7,7,7]
+
+[]
+[3]
+
+[[[]]]
+[[]]
+
+[1,[2,[3,[4,[5,6,7]]]],8,9]
+[1,[2,[3,[4,[5,6,0]]]],8,9]";
+
+    #[test]
+    fn test() {
+        let mut v = vec![Packet::Num(1), Packet::Num(0)];
+        v.sort();
+        assert_eq!(v, vec![Packet::Num(0), Packet::Num(1)]);
+        assert!("[1,1,3,1]".parse::<Packet>().unwrap() < "[1,1,5,1]".parse::<Packet>().unwrap());
+        assert_eq!(
+            "[[8,7,6]]".parse::<Packet>().unwrap(),
+            Packet::List(Box::new(vec![Packet::List(Box::new(vec![
+                Packet::Num(8),
+                Packet::Num(7),
+                Packet::Num(6)
+            ]))]))
+        );
+        let input = processed_input(TEST_INPUT);
+        assert_eq!(part1(&input), 13);
+        assert_eq!(part2(&input), 0);
+        // assert_eq!(both_parts(&input), (0, 0));
+    }
+}