Add day 23

d23.lua

@@ -0,0 +1,189 @@
+function get_param(state, arg)
+    local param_mode = state.mem[state.pos] // (10 ^ (arg + 1)) % 10
+    if #state.mem < state.pos + arg then
+        print(string.format("Error: Opcode too short at end of memory: %d", state.pos))
+        os.exit(false)
+    end
+    local arg = state.mem[state.pos + arg]
+    if param_mode == 0 then
+        arg = arg + 1
+    elseif param_mode == 2 then
+        arg = arg + state.relbase
+    end
+    return arg
+end
+
+function read_mem(state, arg)
+    local param_mode = state.mem[state.pos] // (10 ^ (arg + 1)) % 10
+    local arg = get_param(state, arg)
+    if param_mode == 1 then
+        return arg
+    end
+    arg = state.mem[arg]
+    if not arg then
+        return 0
+    end
+    return arg
+end
+
+function write_mem(state, arg, val)
+    local param_mode = state.mem[state.pos] // (10 ^ (arg + 1)) % 10
+    local arg = get_param(state, arg)
+    if param_mode == 1 then
+        print(string.format("Error: Invalid inmediate write: %d", arg))
+    end
+    state.mem[arg] = val
+end
+
+function interpret(state)
+    if not state.mem then
+        state.mem = state
+    end
+    if not state.pos then
+        state.pos = 1
+        state.relbase = 1
+    end
+    if not state.input then
+        state.input = input_stdin
+    end
+    if not state.output then
+        state.output = output_stdout
+    end
+
+    while true do
+        if #state.mem < state.pos then
+            print(string.format("Instruction pointer ran off of memory"))
+            os.exit(false)
+        end
+
+        local opcode = state.mem[state.pos] % 100
+        local instr_size = 1
+
+        if opcode == 1 then
+            write_mem(state, 3, read_mem(state, 1) + read_mem(state, 2))
+            instr_size = 4
+        elseif opcode == 2 then
+            write_mem(state, 3, read_mem(state, 1) * read_mem(state, 2))
+            instr_size = 4
+        elseif opcode == 3 then
+            local val = state.input()
+            if not val then return true end
+            write_mem(state, 1, val)
+            instr_size = 2
+        elseif opcode == 4 then
+            state.output(read_mem(state, 1))
+            instr_size = 2
+        elseif opcode == 5 then
+            instr_size = 3
+            if read_mem(state, 1) ~= 0 then
+                state.pos = read_mem(state, 2) + 1
+                instr_size = 0
+            end
+        elseif opcode == 6 then
+            instr_size = 3
+            if read_mem(state, 1) == 0 then
+                state.pos = read_mem(state, 2) + 1
+                instr_size = 0
+            end
+        elseif opcode == 7 then
+            write_mem(state, 3, read_mem(state, 1) < read_mem(state, 2) and 1 or 0)
+            instr_size = 4
+        elseif opcode == 8 then
+            write_mem(state, 3, read_mem(state, 1) == read_mem(state, 2) and 1 or 0)
+            instr_size = 4
+        elseif opcode == 9 then
+            state.relbase = state.relbase + read_mem(state, 1)
+            instr_size = 2
+        elseif opcode == 99 then
+            return false
+        else
+            print(string.format("Error: Invalid opcode %d at %d", opcode, state.pos - 1))
+            os.exit(false)
+        end
+
+        state.pos = state.pos + instr_size
+    end
+end
+
+function input_stdin()
+    io.stdout:write("> ")
+    return io.stdin:read("n")
+end
+
+function output_stdout(val)
+    io.stdout:write(val)
+    io.stdout:write("\n")
+end
+
+function input_array(array)
+    function inner()
+        return table.remove(array, 1)
+    end
+    return inner
+end
+
+function output_array(array)
+    function inner(val)
+        table.insert(array, val)
+    end
+    return inner
+end
+
+file = io.open(arg[1])
+program = {}
+for num in string.gmatch(file:read(), "(-?%d+),?") do
+    table.insert(program, tonumber(num))
+end
+file:close()
+
+network = {}
+for i = 1, 50 do
+    computer = {mem={table.unpack(program)}, inp={i - 1}, outp={}}
+    computer.input = input_array(computer.inp)
+    computer.output = output_array(computer.outp)
+    table.insert(network, computer)
+end
+
+nat_seen = {}
+nat = nil
+while true do
+    running = false
+    idle = true
+    for _, computer in ipairs(network) do
+        if #computer.inp == 0 then
+            table.insert(computer.inp, -1)
+        else
+            idle = false
+        end
+        if interpret(computer) then
+            running = true
+        end
+        while #computer.outp > 0 do
+            addr = table.remove(computer.outp, 1)
+            x = table.remove(computer.outp, 1)
+            y = table.remove(computer.outp, 1)
+            if addr == 255 then
+                if not nat then
+                    print("Part 1:", y)
+                end
+                nat = {x, y}
+            else
+                dest = network[addr + 1]
+                table.insert(dest.inp, x)
+                table.insert(dest.inp, y)
+            end
+        end
+    end
+    if idle then
+        if nat_seen[nat[2]] then
+            print("Part 2:", nat[2])
+            break
+        end
+        nat_seen[nat[2]] = true
+        table.insert(network[1].inp, nat[1])
+        table.insert(network[1].inp, nat[2])
+    end
+    if not running then
+        break
+    end
+end