2019-12-19 - Tractor Beam
(original .ipynb)
Day 19 puzzle input is an IntCode program (mine is here) which will models a sort of beam, and when provided with an x/y co-ordinate will output whether the beam is in effect at that position. Part 1 involves finding the number of positions for x and y in the range 0-49 which are affected by the beam. Part 2 involves figuring out the first 100x100 section which can be wholly contained within the beam (position of the top-left corner).
opcode_add = 1
opcode_mul = 2
opcode_read = 3
opcode_write = 4
opcode_jump_true = 5
opcode_jump_false = 6
opcode_lt = 7
opcode_eq = 8
opcode_rebase = 9
opcode_terminate = 99
mode_position = 0
mode_immediate = 1
mode_relative = 2
class IntCodeCpu:
def __init__(self, memory_image):
self.memory = [ x for x in memory_image ] # copy memory image, in case it's reused
self.stalled = True
self.input_buffer = None
self.output_buffer = None
self.pc = 0
self.initialise_opcodes()
self.offset = 0
self.done = False
def start(self, input_buffer, output_buffer, noun=None, verb=None):
self.input_buffer = input_buffer
self.output_buffer = output_buffer
if noun:
self.memory[1] = noun
if verb:
self.memory[2] = verb
return self.run()
def run(self):
instr = self.memory[self.pc]
self.stalled = False
while int(instr) != opcode_terminate and not self.stalled:
(op, modes) = self.decode_instr(instr)
self.pc = op(modes)
instr = self.memory[self.pc]
return self.memory[0]
#-HELPERS-----------------------------
def try_pop_mode(self, modes):
if len(modes) == 0:
return 0
return modes.pop()
def resize_memory(self, target_addr):
self.memory += ([0] * (1 + target_addr - len(self.memory)))
#-DECODE-INSTRUCTIONS-----------------
def initialise_opcodes(self):
self.opcodes = {
opcode_add: self.op_add,
opcode_mul: self.op_mul,
opcode_read: self.op_read,
opcode_write: self.op_write,
opcode_jump_true: self.op_jump_true,
opcode_jump_false: self.op_jump_false,
opcode_lt: self.op_lt,
opcode_eq: self.op_eq,
opcode_rebase: self.op_rebase
}
def decode_instr(self, instr):
instr = str(instr)
opcode = self.decode_op(instr)
modes = self.decode_modes(instr)
if not (opcode in self.opcodes):
raise Exception(f"Invalid opcode {opcode}")
return (self.opcodes[opcode], modes)
def decode_op(self, instr):
if len(instr) > 2:
return int(instr[-2:])
return int(instr)
def decode_modes(self, instr):
if len(instr) > 2:
return [ int(d) for d in instr[:-2]]
return []
#-MICRO-OPS---------------------------
def uop_read(self, value, mode):
if mode == mode_position:
if value >= len(self.memory):
self.resize_memory(value)
return int(self.memory[value])
elif mode == mode_relative:
if self.offset + value >= len(self.memory):
self.resize_memory(self.offset + value)
return int(self.memory[self.offset + value])
elif mode == mode_immediate:
return int(value)
else:
raise Exception("UNKNOWN MODE")
def uop_write(self, dst, value, mode):
if mode == mode_position:
if dst >= len(self.memory):
self.resize_memory(dst)
self.memory[dst] = value
elif mode == mode_relative:
if self.offset + dst >= len(self.memory):
self.resize_memory(self.offset + dst)
self.memory[self.offset + dst] = value
elif mode == mode_immediate:
raise Exception(f"cannot write {value} to literal {dst}")
def uop_cond_jump(self, modes, cond):
param_mode = self.try_pop_mode(modes)
param_raw = int(self.memory[self.pc + 1])
param = self.uop_read(param_raw, param_mode)
dest_mode = self.try_pop_mode(modes)
dest_raw = int(self.memory[self.pc + 2])
dest = self.uop_read(dest_raw, dest_mode)
if cond(param):
return dest
return self.pc + 3
def uop_cmp(self, modes, cmp):
param0_mode = self.try_pop_mode(modes)
param0_raw = int(self.memory[self.pc + 1])
param0 = self.uop_read(param0_raw, param0_mode)
param1_mode = self.try_pop_mode(modes)
param1_raw = int(self.memory[self.pc + 2])
param1 = self.uop_read(param1_raw, param1_mode)
dest_mode = self.try_pop_mode(modes)
dest = int(self.memory[self.pc + 3])
if cmp(param0, param1):
self.uop_write(dest, 1, dest_mode)
else:
self.uop_write(dest, 0, dest_mode)
return self.pc + 4
#-OPCODES-----------------------------
def op_add(self, modes):
arg0_mode = self.try_pop_mode(modes)
arg1_mode = self.try_pop_mode(modes)
dest_mode = self.try_pop_mode(modes)
arg0_raw = int(self.memory[self.pc + 1])
arg1_raw = int(self.memory[self.pc + 2])
dest = int(self.memory[self.pc + 3])
arg0 = self.uop_read(arg0_raw, arg0_mode)
arg1 = self.uop_read(arg1_raw, arg1_mode)
self.uop_write(dest, str(int(arg0) + int(arg1)), dest_mode)
return self.pc + 4
def op_mul(self, modes):
arg0_mode = self.try_pop_mode(modes)
arg1_mode = self.try_pop_mode(modes)
dest_mode = self.try_pop_mode(modes)
arg0_raw = int(self.memory[self.pc + 1])
arg1_raw = int(self.memory[self.pc + 2])
dest = int(self.memory[self.pc + 3])
arg0 = self.uop_read(arg0_raw, arg0_mode)
arg1 = self.uop_read(arg1_raw, arg1_mode)
self.uop_write(dest, str(int(arg0) * int(arg1)), dest_mode)
return self.pc + 4
def op_read(self, modes):
dest_mode = self.try_pop_mode(modes)
dest = int(self.memory[self.pc + 1])
# if the input buffer is empty, we should "stall" and
# resume later
if not self.input_buffer:
self.stalled = True
return self.pc
val = self.input_buffer.pop()
self.uop_write(dest, str(val), dest_mode)
return self.pc + 2
def op_write(self, modes):
src_mode = self.try_pop_mode(modes)
src_raw = int(self.memory[self.pc + 1])
src = self.uop_read(src_raw, src_mode)
self.output_buffer.append(src)
return self.pc + 2
def op_jump_true(self, modes):
return self.uop_cond_jump(modes, lambda x: x != 0)
def op_jump_false(self, modes):
return self.uop_cond_jump(modes, lambda x: x == 0)
def op_lt(self, modes):
return self.uop_cmp(modes, lambda x, y: x < y)
def op_eq(self, modes):
return self.uop_cmp(modes, lambda x, y: x == y)
def op_rebase(self, modes):
param_mode = self.try_pop_mode(modes)
param_raw = int(self.memory[self.pc + 1])
param = self.uop_read(param_raw, param_mode)
self.offset += param
return self.pc + 2
raw_code = open("puzzle_input/day19.txt", "r").read()
code = raw_code.split(",")
points_affected = 0
output = []
output_buffer = []
for row in range(0,50):
current_row = []
for col in range(0, 50):
cpu = IntCodeCpu(code)
cpu.start([row, col], output_buffer)
assert 1 == len(output_buffer)
points_affected += output_buffer[0]
output_buffer = []
output.append(current_row)
print(points_affected)
217
def in_beam(row, col):
# is it necessary to create new cpu each time?
cpu = IntCodeCpu(code)
output_buffer = []
input_buffer = [row, col]
cpu.start(input_buffer, output_buffer)
assert 1 == len(output_buffer)
return output_buffer[0] == 1
def beam_at_row(row, start_col):
beam_start = start_col
beam_width = 0
col = start_col
# mine has an empty area in rows
# 1 and 2 so use precomputed values
# yes this is yet another horrible hack
if row < 3:
return [
(0,1),
(0,0),
(0,0)
][row]
# seek to the beam start
while not in_beam(row, col):
beam_start += 1
col += 1
# continue to beam end
while in_beam(row, col):
beam_width += 1
col += 1
return (beam_start, beam_width)
def beam_can_contain_cube(beam_data, cube_size):
current_beam_index = len(beam_data) - 1
current_beam_start, current_beam_width = beam_data[current_beam_index]
# so we need to check if:
# 0. there have been at least enough beams (we'll be looking back in the beam_data by cube_size)
if current_beam_index - cube_size < 0:
return False
# 1. the beam width starting at the current line < cube_size
if current_beam_width < cube_size:
return False
# 2. the same point at line (current_beam_index - cube_size) is in beam
start_beam_index = current_beam_index - (cube_size - 1)
start_beam_start, start_beam_width = beam_data[start_beam_index]
if current_beam_start >= start_beam_start + start_beam_width:
return False
# 3. there's enough beam at that ^^^ line afterwards to contain the beam
if current_beam_start + cube_size > start_beam_start + start_beam_width:
return False
return True
#################
target_cube = 100
# seed our beam with a few rows to get going
beam = [ beam_at_row(n, 0) for n in range(0, 20) ]
current_beam = len(beam)
start_col = 2
while not(beam_can_contain_cube(beam, target_cube)):
current = beam_at_row(current_beam, start_col-1)
start_col, current_size = current
beam.append(current)
current_beam += 1
cube_end_row = current_beam - 1
cube_start_row = cube_end_row - (target_cube - 1)
current_beam_start_col, current_beam_width = beam[-1]
print((current_beam_start_col * 10000) + cube_start_row)
6840937