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95 lines
2.4 KiB
95 lines
2.4 KiB
function get_arg(mem, pos, arg)
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local param_mode = mem[pos] // (10 ** (arg + 1)) % 10
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if #mem < pos + arg then
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print(string.format("Error: Opcode too short at end of memory: %d", pos))
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os.exit(false)
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end
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local arg = mem[pos + arg]
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if param_mode == 0 then
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arg = arg + 1
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if #mem < arg then
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print(string.format("Error: Memory offset out of bounds: %d", arg))
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os.exit(false)
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end
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end
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return arg
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end
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function get_param(mem, pos, arg)
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local param_mode = mem[pos] // (10 ** (arg + 1)) % 10
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local arg = get_arg(mem, pos, arg)
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if param_mode == 0 then
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return mem[arg]
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end
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return arg
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end
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function interpret(mem)
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local pos = 1
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while true do
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if #mem < pos then
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print(string.format("Instruction pointer ran off of memory"))
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os.exit(false)
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end
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local opcode = mem[pos] % 100
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if opcode == 1 or opcode == 2 then
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local arg1 = get_param(mem, pos, 1)
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local arg2 = get_param(mem, pos, 2)
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local res = get_arg(mem, pos, 3)
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if opcode == 1 then
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mem[res] = arg1 + arg2
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else
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mem[res] = arg1 * arg2
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end
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pos = pos + 4
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elseif opcode == 3 then
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local arg = get_arg(mem, pos, 1)
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io.stdout:write("> ")
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local val = io.stdin:read("n")
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io.stdout:write(val)
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io.stdout:write("\n")
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mem[arg] = val
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pos = pos + 2
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elseif opcode == 4 then
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io.stdout:write(get_param(mem, pos, 1))
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pos = pos + 2
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elseif opcode == 99 then
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return
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else
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print(string.format("Error: Invalid opcode %d at %d", opcode, pos - 1))
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os.exit(false)
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end
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end
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end
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file = io.open(arg[1])
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memory = {}
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for num in string.gmatch(file:read(), "(%d+),") do
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table.insert(memory, tonumber(num))
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end
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file:close()
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memory_p1 = {table.unpack(memory)}
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memory_p1[2] = 12
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memory_p1[3] = 2
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interpret(memory_p1)
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print("Part 1:", memory_p1[1])
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-- Brute force
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for noun = 0, 99 do
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for verb = 0, 99 do
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memory_p2 = {table.unpack(memory)}
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memory_p2[2] = noun
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memory_p2[3] = verb
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interpret(memory_p2)
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if memory_p2[1] == 19690720 then
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print("Part 2:", 100 * noun + verb)
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os.exit(true)
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end
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end
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end
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