Initial commit

16.jl

@@ -0,0 +1,116 @@
+using Pkg
+Pkg.add("Match")
+using Match
+
+include("utils.jl")
+
+function parse_input(filename)
+    reverse(collect(collect(non_empty_lines(filename))[1]))
+end
+
+mutable struct BinaryReader
+    input
+    rest
+    BinaryReader(input) = new(input, [])
+end
+
+function fill_rest(reader)
+    char = pop!(reader.input)
+    code = codepoint(char)
+    number = code < 0x3A ? code - 0x30 : code - (0x41 - 10)
+    reader.rest = reverse(parse.(Int, collect(string(number, base=2, pad=4))))
+end
+
+function read_bits(reader, count)
+    result = []
+    while length(result) < count
+        if length(reader.rest) == 0
+            fill_rest(reader)
+        end
+        push!(result, pop!(reader.rest))
+    end
+    result
+end
+
+function reader_length(reader)
+    length(reader.rest) + length(reader.input) * 4
+end
+
+function to_int(bits)
+    parse(Int, reduce(*, string.(bits)), base=2)
+end
+
+function parse_literal(reader, version)
+    result = []
+    cont = 1
+    while cont == 1
+        cont = read_bits(reader, 1)[1]
+        result = [result; read_bits(reader, 4)]
+    end
+    (version, 4, to_int(result))
+end
+
+function parse_operator(reader, version, type)
+    length_type = read_bits(reader, 1)[1]
+    subpackets = []
+    if length_type == 0
+        subpacket_bits = to_int(read_bits(reader, 15))
+        start_remaining = reader_length(reader)
+        while reader_length(reader) + subpacket_bits > start_remaining
+            push!(subpackets, parse_packet(reader))
+        end
+    else
+        subpacket_count = to_int(read_bits(reader, 11))
+        for _ in 1:subpacket_count
+            push!(subpackets, parse_packet(reader))
+        end
+    end
+    (version, type, subpackets)
+end
+
+function parse_packet(reader)
+    version = to_int(read_bits(reader, 3))
+    type = to_int(read_bits(reader, 3))
+    if type == 4
+        parse_literal(reader, version)
+    else
+        parse_operator(reader, version, type)
+    end
+end
+
+function sum_versions(packet)
+    result = packet[1]
+    if packet[2] != 4
+        result += reduce(+, sum_versions.(packet[3]))
+    end
+    result
+end
+
+function solution16_1()
+    input = parse_input("16.data")
+    reader = BinaryReader(input)
+    packet = parse_packet(reader)
+    sum_versions(packet)
+end
+
+function value(packet)
+    @match packet[2] begin
+        0 => reduce(+, value.(packet[3]))
+        1 => reduce(*, value.(packet[3]))
+        2 => reduce(min, value.(packet[3]))
+        3 => reduce(max, value.(packet[3]))
+        4 => packet[3]
+        5 => value(packet[3][1]) > value(packet[3][2]) ? 1 : 0
+        6 => value(packet[3][1]) < value(packet[3][2]) ? 1 : 0
+        7 => value(packet[3][1]) == value(packet[3][2]) ? 1 : 0
+    end
+end
+
+function solution16_2()
+    input = parse_input("16.data")
+    reader = BinaryReader(input)
+    packet = parse_packet(reader)
+    value(packet)
+end
+
+solution16_2()