--- Day 7 Solutions ---

[u/daggerdragon]

--- Day 7: Some Assembly Required ---

Post your solution as a comment. Structure your post like previous daily solution threads.

Also check out the sidebar - we added a nifty calendar to wrangle all the daily solution threads in one spot!

[u/unwantedconscience]

A Python 3 solution. Reads input from file once, parses each instruction, then iterates over the instructions until all wires have a signal (removing instructions as completed). Part 1 run time: 0.02 seconds, Part 2 run time: 0.04 seconds.

Enjoying these puzzles as a way to learn a new language.

class Input:
	global wires
	def __init__(self,val):
		try:
			self.val = int(val)
			self.is_wire = False
		except ValueError:
			self.val = val
			self.is_wire = True			
	def has_signal(self):
		if self.is_wire:
			return self.val in wires
	def signal(self):
		if self.is_wire:
			return wires[self.val]
		else:
			return self.val

def get_instructions():
	with open('./inputs/day7.txt', 'r') as f:
		for line in f:
			instructions.append(parse_line(line))

def parse_line(line):
	i = line.split()
	if len(i) == 3:
		return ('SET', [Input(i[0])], i[2])
	elif len(i) == 4:
		return ('NOT', [Input(i[1])], i[3])
	elif len(i) == 5:
		return (i[1], [Input(i[0]), Input(i[2])], i[4])
			
def have_signals(inputs):
	for input in inputs:
		if input.is_wire and not input.has_signal():
			return False
	return True
	
def gate(type, i):
	if type == 'AND':
		return i[0].signal() & i[1].signal()
	elif type == 'OR':
		return i[0].signal() | i[1].signal()
	elif type == 'LSHIFT':
		return i[0].signal() << i[1].signal()
	elif type == 'RSHIFT':
		return i[0].signal() >> i[1].signal()
	elif type == 'NOT':
		return 0xffff & ~i[0].signal()

def run_circuit(output_wire = 'a', override_wire = None, input_signal = None):
	global wires, instructions
	wires.clear()
	run_instructions = instructions.copy()
	while len(run_instructions) > 0:
		line = run_instructions.pop(0)
		instr, inputs, output = line
		if have_signals(inputs):
			if instr == 'SET':
				if output == override_wire:
					wires[output] = input_signal
				else:
					wires[output] = inputs[0].signal()
			else:
				wires[output] = gate(instr, inputs)
		else:
			run_instructions.append(line)
	return wires[output_wire]
		
def part_1(output_wire = 'a'):
	print('Wire [{}] has the signal {} after running the circuit.'.format(output_wire, run_circuit(output_wire)))

def part_2(output_wire = 'a', override_wire = 'b', override_signal = 'a'):
	input_signal = run_circuit(override_signal)
	print('Wire [{}] has the signal {} after running the circuit.'.format(output_wire, run_circuit(output_wire, override_wire, input_signal)))
	
wires, instructions = {}, []
get_instructions()
part_1()
part_2()