2021: day16: part 2
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78f059b65c
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@ -1,7 +1,7 @@
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use std::fmt::Write;
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use std::ops::Range;
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use anyhow::{Context, Result};
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use anyhow::{bail, Context, Result};
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use bitvec::prelude::*;
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const INPUT: &str = include_str!("../input/day16.txt");
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@ -10,6 +10,7 @@ pub fn run() -> Result<String> {
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let mut res = String::with_capacity(128);
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writeln!(res, "part 1: {}", part1(INPUT)?)?;
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writeln!(res, "part 2: {}", part2(INPUT)?)?;
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Ok(res)
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}
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@ -20,6 +21,12 @@ fn part1(input: &str) -> Result<u64> {
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Ok(packet.version_sum())
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}
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fn part2(input: &str) -> Result<u64> {
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let packet: Packet = input.parse()?;
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Ok(packet.value())
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}
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#[derive(PartialEq, Eq, Debug)]
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enum PacketType {
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Litteral(LitteralPacket),
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@ -44,6 +51,48 @@ impl Packet {
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}
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}
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}
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fn value(&self) -> u64 {
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match &self.packet {
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PacketType::Litteral(lit) => lit.value,
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PacketType::Operator(op) => match op.op_type {
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OperatorType::Sum => op.sub_packets.iter().map(Packet::value).sum(),
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OperatorType::Product => op.sub_packets.iter().map(Packet::value).product(),
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OperatorType::Minimum => op.sub_packets.iter().map(Packet::value).min().unwrap(),
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OperatorType::Maximum => op.sub_packets.iter().map(Packet::value).max().unwrap(),
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OperatorType::GreaterThan => {
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debug_assert_eq!(op.sub_packets.len(), 2);
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let pack1 = &op.sub_packets[0];
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let pack2 = &op.sub_packets[1];
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if pack1.value() > pack2.value() {
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1
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} else {
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0
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}
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}
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OperatorType::LessThan => {
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debug_assert_eq!(op.sub_packets.len(), 2);
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let pack1 = &op.sub_packets[0];
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let pack2 = &op.sub_packets[1];
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if pack1.value() < pack2.value() {
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1
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} else {
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0
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}
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}
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OperatorType::EqualTo => {
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debug_assert_eq!(op.sub_packets.len(), 2);
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let pack1 = &op.sub_packets[0];
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let pack2 = &op.sub_packets[1];
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if pack1.value() == pack2.value() {
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1
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} else {
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0
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}
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}
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},
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}
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}
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}
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#[derive(PartialEq, Eq, Debug)]
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@ -51,9 +100,21 @@ struct LitteralPacket {
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value: u64,
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}
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#[derive(PartialEq, Eq, Debug)]
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enum OperatorType {
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Sum,
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Product,
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Minimum,
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Maximum,
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GreaterThan,
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LessThan,
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EqualTo,
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}
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#[derive(PartialEq, Eq, Debug)]
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struct OperatorPacket {
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sub_packets: Vec<Packet>,
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op_type: OperatorType,
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}
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impl std::str::FromStr for Packet {
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@ -148,11 +209,26 @@ where
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SUBPACKET_START_INDEX_TLID0 + length
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};
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let op_type = match type_id {
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0 => OperatorType::Sum,
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1 => OperatorType::Product,
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2 => OperatorType::Minimum,
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3 => OperatorType::Maximum,
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4 => unreachable!("impossible, would parse as a litteral packet"),
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5 => OperatorType::GreaterThan,
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6 => OperatorType::LessThan,
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7 => OperatorType::EqualTo,
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_ => bail!("unknown type id: {}", type_id),
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};
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Ok(Packet {
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version,
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type_id,
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bits_used: len,
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packet: PacketType::Operator(OperatorPacket { sub_packets }),
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packet: PacketType::Operator(OperatorPacket {
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sub_packets,
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op_type,
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}),
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})
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}
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}
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@ -163,19 +239,19 @@ where
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mod tests {
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use super::*;
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const PROVIDED1: &str = "D2FE28";
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const PROVIDED2: &str = "38006F45291200";
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const PROVIDED3: &str = "EE00D40C823060";
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const PART1_PROVIDED1: &str = "D2FE28";
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const PART1_PROVIDED2: &str = "38006F45291200";
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const PART1_PROVIDED3: &str = "EE00D40C823060";
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const PROVIDED4: &str = "8A004A801A8002F478";
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const PROVIDED5: &str = "620080001611562C8802118E34";
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const PROVIDED6: &str = "C0015000016115A2E0802F182340";
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const PROVIDED7: &str = "A0016C880162017C3686B18A3D4780";
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const PART1_PROVIDED4: &str = "8A004A801A8002F478";
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const PART1_PROVIDED5: &str = "620080001611562C8802118E34";
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const PART1_PROVIDED6: &str = "C0015000016115A2E0802F182340";
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const PART1_PROVIDED7: &str = "A0016C880162017C3686B18A3D4780";
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#[test]
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fn part1_provided() {
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assert_eq!(
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PROVIDED1.parse::<Packet>().unwrap(),
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PART1_PROVIDED1.parse::<Packet>().unwrap(),
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Packet {
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version: 6,
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type_id: 4,
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@ -185,7 +261,7 @@ mod tests {
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);
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assert_eq!(
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PROVIDED2.parse::<Packet>().unwrap(),
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PART1_PROVIDED2.parse::<Packet>().unwrap(),
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Packet {
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version: 1,
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type_id: 6,
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@ -205,12 +281,13 @@ mod tests {
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packet: PacketType::Litteral(LitteralPacket { value: 20 })
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},
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],
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op_type: OperatorType::LessThan,
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}),
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}
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);
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assert_eq!(
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PROVIDED3.parse::<Packet>().unwrap(),
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PART1_PROVIDED3.parse::<Packet>().unwrap(),
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Packet {
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version: 7,
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type_id: 3,
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@ -236,18 +313,45 @@ mod tests {
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packet: PacketType::Litteral(LitteralPacket { value: 3 })
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},
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],
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op_type: OperatorType::Maximum,
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}),
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}
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);
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assert_eq!(PROVIDED4.parse::<Packet>().unwrap().version_sum(), 16);
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assert_eq!(PROVIDED5.parse::<Packet>().unwrap().version_sum(), 12);
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assert_eq!(PROVIDED6.parse::<Packet>().unwrap().version_sum(), 23);
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assert_eq!(PROVIDED7.parse::<Packet>().unwrap().version_sum(), 31);
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assert_eq!(PART1_PROVIDED4.parse::<Packet>().unwrap().version_sum(), 16);
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assert_eq!(PART1_PROVIDED5.parse::<Packet>().unwrap().version_sum(), 12);
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assert_eq!(PART1_PROVIDED6.parse::<Packet>().unwrap().version_sum(), 23);
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assert_eq!(PART1_PROVIDED7.parse::<Packet>().unwrap().version_sum(), 31);
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}
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#[test]
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fn part1_real() {
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assert_eq!(part1(INPUT).unwrap(), 925);
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}
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const PART2_PROVIDED1: &str = "C200B40A82";
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const PART2_PROVIDED2: &str = "04005AC33890";
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const PART2_PROVIDED3: &str = "880086C3E88112";
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const PART2_PROVIDED4: &str = "CE00C43D881120";
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const PART2_PROVIDED5: &str = "D8005AC2A8F0";
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const PART2_PROVIDED6: &str = "F600BC2D8F";
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const PART2_PROVIDED7: &str = "9C005AC2F8F0";
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const PART2_PROVIDED8: &str = "9C0141080250320F1802104A08";
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#[test]
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fn part2_provided() {
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assert_eq!(part2(PART2_PROVIDED1).unwrap(), 3);
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assert_eq!(part2(PART2_PROVIDED2).unwrap(), 54);
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assert_eq!(part2(PART2_PROVIDED3).unwrap(), 7);
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assert_eq!(part2(PART2_PROVIDED4).unwrap(), 9);
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assert_eq!(part2(PART2_PROVIDED5).unwrap(), 1);
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assert_eq!(part2(PART2_PROVIDED6).unwrap(), 0);
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assert_eq!(part2(PART2_PROVIDED7).unwrap(), 0);
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assert_eq!(part2(PART2_PROVIDED8).unwrap(), 1);
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}
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#[test]
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fn part2_real() {
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assert_eq!(part2(INPUT).unwrap(), 342997120375);
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}
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}
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