2021 Day 16 Complete

2021/day16/input

@@ -0,0 +1 @@
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

2021/day16/main.go

@@ -0,0 +1,240 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+func main() {
+	inp := h.StdinToString()
+	var arg string
+	if len(os.Args) > 1 {
+		arg = os.Args[1]
+	}
+
+	p := ParsePacket(inp)
+	if arg == "--json" {
+		fmt.Println(p.Json())
+	} else {
+		fmt.Println("# Part 1")
+		fmt.Println("Version Sum:", CalculateVersionSum(p))
+		fmt.Println()
+		fmt.Println("# Part 2")
+		fmt.Println("Value:", p.value)
+	}
+}
+
+func CalculateVersionSum(p *Packet) int {
+	sum := p.version
+	for s := range p.packets {
+		sum += CalculateVersionSum(p.packets[s])
+	}
+	return sum
+}
+
+const (
+	PacketTypeSum = iota
+	PacketTypeProduct
+	PacketTypeMin
+	PacketTypeMax
+	PacketTypeLiteral
+	PacketTypeGreater
+	PacketTypeLess
+	PacketTypeEqual
+
+	LengthTypeBits       = 0
+	LengthTypeSubPackets = 1
+)
+
+type Packet struct {
+	version    int
+	packetType int
+
+	value int
+
+	// Operator
+	lengthTypeId int
+	subLength    int
+
+	// Sub-packets
+	packets []*Packet
+
+	binaryString string
+}
+
+func ParsePacket(inp string) *Packet {
+	var bin string
+	for i := 0; i < len(inp); i += 2 {
+		if len(inp) >= i+2 {
+			bin += fmt.Sprintf("%08b", HexToByte(inp[i:i+2]))
+		}
+	}
+	return ParseBinaryPacket(bin)
+}
+
+func ParseBinaryPacket(inp string) *Packet {
+	p := Packet{
+		binaryString: inp,
+	}
+	// Parse the version
+	for i := 0; i < 3; i++ {
+		p.version = p.version << 1
+		if p.binaryString[i] == '1' {
+			p.version |= 1
+		}
+	}
+	for i := 3; i < 6; i++ {
+		p.packetType = p.packetType << 1
+		if p.binaryString[i] == '1' {
+			p.packetType |= 1
+		}
+	}
+	if p.packetType == PacketTypeLiteral {
+		p.parseLiteral()
+	} else {
+		p.parseOperator()
+	}
+	return &p
+}
+
+func (p *Packet) parseLiteral() {
+	// The bits for the literal start at bit 7
+	// Every 5 bits is a chunk of the literal
+	ptr := 6
+	more := true
+	for more {
+		more = (p.binaryString[ptr] == '1')
+		ptr++
+		for i := 0; i < 4; i++ {
+			p.value = p.value << 1
+			if p.binaryString[ptr] == '1' {
+				p.value |= 1
+			}
+			ptr++
+		}
+	}
+	p.binaryString = p.binaryString[:ptr]
+}
+
+func (p *Packet) parseOperator() {
+	ptr := 6
+	p.lengthTypeId = int(p.binaryString[ptr] - '0')
+	ptr++
+	if p.lengthTypeId == LengthTypeBits {
+		for i := 0; i < 15; i++ {
+			p.subLength = p.subLength << 1
+			if p.binaryString[ptr] == '1' {
+				p.subLength |= 1
+			}
+			ptr++
+		}
+		length := p.subLength
+		for length > 0 {
+			sp := ParseBinaryPacket(p.binaryString[ptr:])
+			p.packets = append(p.packets, sp)
+			ptr += len(sp.binaryString)
+			length -= len(sp.binaryString)
+		}
+		p.binaryString = p.binaryString[:ptr]
+	} else if p.lengthTypeId == LengthTypeSubPackets {
+		for i := 0; i < 11; i++ {
+			p.subLength = p.subLength << 1
+			if p.binaryString[ptr] == '1' {
+				p.subLength |= 1
+			}
+			ptr++
+		}
+		length := p.subLength
+		for length > 0 {
+			sp := ParseBinaryPacket(p.binaryString[ptr:])
+			p.packets = append(p.packets, sp)
+			ptr += len(sp.binaryString)
+			length--
+		}
+		p.binaryString = p.binaryString[:ptr]
+	}
+	switch p.packetType {
+	case PacketTypeSum:
+		for _, sp := range p.packets {
+			p.value += sp.value
+		}
+	case PacketTypeProduct:
+		p.value = 1
+		for _, sp := range p.packets {
+			p.value *= sp.value
+		}
+	case PacketTypeMin:
+		p.value = h.MAX_INT
+		for _, sp := range p.packets {
+			if sp.value < p.value {
+				p.value = sp.value
+			}
+		}
+	case PacketTypeMax:
+		p.value = h.MIN_INT
+		for _, sp := range p.packets {
+			if sp.value > p.value {
+				p.value = sp.value
+			}
+		}
+	case PacketTypeGreater:
+		if len(p.packets) == 2 && (p.packets[0].value > p.packets[1].value) {
+			p.value = 1
+		} else {
+			p.value = 0
+		}
+	case PacketTypeLess:
+		if len(p.packets) == 2 && (p.packets[0].value < p.packets[1].value) {
+			p.value = 1
+		} else {
+			p.value = 0
+		}
+	case PacketTypeEqual:
+		if len(p.packets) == 2 && (p.packets[0].value == p.packets[1].value) {
+			p.value = 1
+		} else {
+			p.value = 0
+		}
+	}
+}
+
+func (p Packet) Json() string {
+	ret := fmt.Sprintf("{\"version\":%d, \"type\":%d, \"value\":%d,", p.version, p.packetType, p.value)
+	ret += "\"packets\":["
+	for i := range p.packets {
+		ret += fmt.Sprintf("%s", p.packets[i].String())
+		if i < len(p.packets)-1 {
+			ret += ","
+		}
+	}
+	ret += fmt.Sprintf("],\"binary\":\"%s\"}", p.binaryString)
+	return ret
+}
+
+func (p Packet) String() string {
+	if p.packetType == PacketTypeLiteral {
+		return fmt.Sprintf("%d", p.value)
+	} else {
+		return p.Json()
+	}
+}
+
+func HexToByte(h string) byte {
+	var b byte
+	for i := range h {
+		var wrk byte
+		if h[i] >= '0' && h[i] <= '9' {
+			wrk = byte(h[i] - '0')
+		} else if h[i] >= 'A' && h[i] <= 'F' {
+			wrk = byte(h[i]-'A') + 10
+		}
+		if i == 0 {
+			b = wrk << 4
+		} else {
+			b |= wrk
+		}
+	}
+	return b
+}

2021/day16/packet_literal2021

@@ -0,0 +1 @@
+D2FE28

2021/day16/packet_literal2021_cruft

@@ -0,0 +1 @@
+D2FE28FEDCBA987654321

2021/day16/packet_operator0

@@ -0,0 +1 @@
+38006F45291200

2021/day16/packet_operator0_cruft

@@ -0,0 +1 @@
+38006F45291200FEDCBA0987654321

2021/day16/packet_operator1

@@ -0,0 +1 @@
+EE00D40C823060

2021/day16/test.json

@@ -0,0 +1 @@
+{"version":0, "type":1, "binary":"00000100000000000101101011000011001110001001",'packets':[6,9]}

2021/day16/testinput1

@@ -0,0 +1 @@
+8A004A801A8002F478

2021/day16/testinput2

@@ -0,0 +1 @@
+620080001611562C8802118E34

2021/day16/testinput3

@@ -0,0 +1 @@
+C0015000016115A2E0802F182340

2021/day16/testinput4

@@ -0,0 +1 @@
+A0016C880162017C3686B18A3D4780