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| 1 | +import java.lang.Long.parseLong |
| 2 | +import scala.annotation.switch |
| 3 | +import scala.collection.mutable.ArrayBuffer |
| 4 | +import scala.io.Source |
| 5 | + |
| 6 | +object Const { |
| 7 | + val inputFile = "./input.txt" |
| 8 | +} |
| 9 | + |
| 10 | +object PacketUtility { |
| 11 | + val valuePacketId = 4 |
| 12 | + |
| 13 | + def GetPacketVersionAndType(packet: String): (Int, Int) = { |
| 14 | + val version = Integer.parseUnsignedInt(packet.substring(0, 3), 2) |
| 15 | + val id = Integer.parseUnsignedInt(packet.substring(3, 6), 2) |
| 16 | + (version, id) |
| 17 | + } |
| 18 | + |
| 19 | + def GetNextPacket(packet: String): Packet = { |
| 20 | + val (version, id) = GetPacketVersionAndType(packet) |
| 21 | + if(id == valuePacketId) { // Literal Value Packet |
| 22 | + var i = 6 |
| 23 | + var bits = "" |
| 24 | + while(true) { |
| 25 | + for(j <- 1 until 5) { |
| 26 | + bits += packet(i+j) |
| 27 | + } |
| 28 | + if(packet(i) == '0') { |
| 29 | + return new ValuePacket(version, id, i+5, parseLong(bits, 2)) |
| 30 | + } |
| 31 | + i += 5 |
| 32 | + } |
| 33 | + null |
| 34 | + } |
| 35 | + else { // Operator Packet |
| 36 | + val subPackets = new ArrayBuffer[Packet]() |
| 37 | + var totalLength = 7 |
| 38 | + |
| 39 | + if(packet(6) == '0') { // We know length of subPackets |
| 40 | + totalLength += 15 |
| 41 | + var nextSubPacketIndex = 22 |
| 42 | + val totalSubPacketsLength = Integer.parseUnsignedInt(packet.substring(7, nextSubPacketIndex),2) |
| 43 | + var foundSubPacketsLength = 0 |
| 44 | + while(foundSubPacketsLength < totalSubPacketsLength) { |
| 45 | + val nextSubPacket = GetNextPacket(packet.substring(nextSubPacketIndex)) |
| 46 | + nextSubPacketIndex += nextSubPacket.length |
| 47 | + foundSubPacketsLength += nextSubPacket.length |
| 48 | + subPackets.append(nextSubPacket) |
| 49 | + } |
| 50 | + } |
| 51 | + else { // We know amount of subPackets |
| 52 | + totalLength += 11 |
| 53 | + var nextSubPacketIndex = 18 |
| 54 | + val numberOfSubPackets = Integer.parseUnsignedInt(packet.substring(7, nextSubPacketIndex),2) |
| 55 | + for(_ <- 0 until numberOfSubPackets) { |
| 56 | + val nextSubPacket = GetNextPacket(packet.substring(nextSubPacketIndex)) |
| 57 | + nextSubPacketIndex += nextSubPacket.length |
| 58 | + subPackets.append(nextSubPacket) |
| 59 | + } |
| 60 | + } |
| 61 | + |
| 62 | + for(p <- subPackets) { |
| 63 | + totalLength += p.length |
| 64 | + } |
| 65 | + |
| 66 | + new OperatorPacket(version, id, totalLength, subPackets.toArray) |
| 67 | + } |
| 68 | + } |
| 69 | +} |
| 70 | + |
| 71 | +abstract class Packet(val version: Int, val id: Int, val length: Int) { |
| 72 | + def getValue: Long |
| 73 | + def getTotalVersion: Int = { |
| 74 | + version |
| 75 | + } |
| 76 | + |
| 77 | + override def toString: String = { |
| 78 | + s"Packet (Ver: $version, Id: $id, Length: $length)" |
| 79 | + } |
| 80 | +} |
| 81 | + |
| 82 | +class ValuePacket(override val version: Int, override val id: Int, override val length: Int, var value: Long) extends Packet(version, id, length) { |
| 83 | + override def getValue: Long = { |
| 84 | + value |
| 85 | + } |
| 86 | + |
| 87 | + override def toString: String = { |
| 88 | + s"${super.toString}: Value = $value" |
| 89 | + } |
| 90 | +} |
| 91 | + |
| 92 | +class OperatorPacket(override val version: Int, override val id: Int, override val length: Int, val subPackets: Array[Packet]) extends Packet(version, id, length) { |
| 93 | + def getValue: Long = { |
| 94 | + (id: @switch) match { |
| 95 | + case 0 => subPackets.foldLeft(0L)((v, packet) => v + packet.getValue) |
| 96 | + case 1 => subPackets.foldLeft(1L)((v, packet) => v * packet.getValue) |
| 97 | + case 2 => subPackets.map(packet => packet.getValue).min |
| 98 | + case 3 => subPackets.map(packet => packet.getValue).max |
| 99 | + case 5 => if (subPackets(0).getValue > subPackets(1).getValue) 1 else 0 |
| 100 | + case 6 => if (subPackets(0).getValue < subPackets(1).getValue) 1 else 0 |
| 101 | + case 7 => if (subPackets(0).getValue == subPackets(1).getValue) 1 else 0 |
| 102 | + } |
| 103 | + } |
| 104 | + |
| 105 | + override def getTotalVersion: Int = { |
| 106 | + subPackets.foldLeft(version)((last, packet) => last + packet.getTotalVersion) |
| 107 | + } |
| 108 | + |
| 109 | + override def toString: String = { |
| 110 | + s"${super.toString}: SubPackets: ${subPackets.length}" |
| 111 | + } |
| 112 | +} |
| 113 | + |
| 114 | +object Main extends App { |
| 115 | + val fileSource = Source.fromFile(Const.inputFile) |
| 116 | + var bits = fileSource.getLines.toList.head.map(c => String.format("%1$4s" ,Integer.parseUnsignedInt(c.toString, 16).toBinaryString).replace(' ', '0')).foldLeft("")((prev, n) => prev.concat(n)) |
| 117 | + fileSource.close |
| 118 | + |
| 119 | + val packet = PacketUtility.GetNextPacket(bits) |
| 120 | + |
| 121 | + println(s"Part 1: ${packet.getTotalVersion}") |
| 122 | + println(s"Part 2: ${packet.getValue}") |
| 123 | +} |
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