tests all pass, but I'm parsing the real input tree slightly wrong

16/main.go

@@ -111,12 +111,15 @@ func parsePackets(stream []uint8) (int, packet) {
 		size, subpacketlength := getSubpacketLength(stream[6], stream[7:])
 		for {
 			consumed, subs := parsePackets(stream[7+size+parsed:])
+			if consumed == 0 {
+				return parsed + 7 + size, parsedPacket
+			}
 			parsedPacket.subPackets = append(parsedPacket.subPackets, subs)
 			parsed += consumed
 			if size == 11 && len(parsedPacket.subPackets) == subpacketlength {
 				return parsed + 7 + size, parsedPacket
 
-			} else if size == 15 && parsed > subpacketlength || consumed == 0 {
+			} else if size == 15 && parsed > subpacketlength {
 				return parsed + 7 + size, parsedPacket
 			}
 		}
@@ -144,10 +147,97 @@ func partOne() {
 	fmt.Println(countVersions(parsedPacket))
 }
 
+func solve(p packet) int {
+	switch p.typeID {
+	case 0: // sum
+		if len(p.subPackets) == 1 {
+			return solve(p.subPackets[0])
+		} else {
+			acc := 0
+			for _, v := range p.subPackets {
+				acc += solve(v)
+			}
+			return acc
+		}
+	case 1: // product
+		if len(p.subPackets) == 1 {
+			return solve(p.subPackets[0])
+		} else {
+			acc := solve(p.subPackets[0])
+			for _, v := range p.subPackets[1:] {
+				acc *= solve(v)
+			}
+			return acc
+		}
+	case 2: // min
+		if len(p.subPackets) == 1 {
+			return solve(p.subPackets[0])
+		} else {
+			acc := solve(p.subPackets[0])
+			for _, v := range p.subPackets[1:] {
+				t := solve(v)
+				if t < acc {
+					acc = t
+				}
+			}
+			return acc
+		}
+	case 3: // max
+		if len(p.subPackets) == 1 {
+			return solve(p.subPackets[0])
+		} else {
+			acc := solve(p.subPackets[0])
+			for _, v := range p.subPackets[1:] {
+				t := solve(v)
+				if t > acc {
+					acc = t
+				}
+			}
+			return acc
+		}
+	case 4: // number
+		return p.encodedNumber
+	case 5: // >
+		if len(p.subPackets) != 2 {
+			panic(fmt.Sprintf("recevied type 5 packet with %d subpackets", len(p.subPackets)))
+		}
+		if solve(p.subPackets[0]) > solve(p.subPackets[1]) {
+			return 1
+		} else {
+			return 0
+		}
+	case 6: // <
+		if len(p.subPackets) != 2 {
+			panic(fmt.Sprintf("recevied type 6 packet with %d subpackets", len(p.subPackets)))
+		}
+		if solve(p.subPackets[0]) < solve(p.subPackets[1]) {
+			return 1
+		} else {
+			return 0
+		}
+	case 7: // ==
+		if len(p.subPackets) != 2 {
+			panic(fmt.Sprintf("recevied type 7 packet with %d subpackets", len(p.subPackets)))
+		}
+		if solve(p.subPackets[0]) == solve(p.subPackets[1]) {
+			return 1
+		} else {
+			return 0
+		}
+	default:
+		panic("unknown packet type")
+	}
+}
+
 func partTwo() {
 	scanner := makeScanner(false)
 
-	for scanner.Scan() {
-		// line := scanner.Text()
+	scanner.Scan()
+	line := scanner.Text()
+	stream := []uint8{}
+	for _, hex := range line {
+		stream = append(stream, hexMap[hex]...)
 	}
+	_, parsedPacket := parsePackets(stream)
+	fmt.Println(solve(parsedPacket))
 }

16/main_test.go

@@ -59,3 +59,28 @@ func TestCases(t *testing.T) {
 		}
 	}
 }
+
+func TestSolving(t *testing.T) {
+	inputs := map[string]int{
+		"C200B40A82":                 3,
+		"04005AC33890":               54,
+		"880086C3E88112":             7,
+		"CE00C43D881120":             9,
+		"D8005AC2A8F0":               1,
+		"F600BC2D8F":                 0,
+		"9C005AC2F8F0":               0,
+		"9C0141080250320F1802104A08": 1,
+	}
+
+	for c, r := range inputs {
+		stream := []uint8{}
+		for _, hex := range c {
+			stream = append(stream, hexMap[hex]...)
+		}
+		_, parsedPacket := parsePackets(stream)
+		if r != solve(parsedPacket) {
+			t.Log(c, solve(parsedPacket))
+			t.Fail()
+		}
+	}
+}