Its not much but its honest work

Author: fschatbot

2024/17.py

@@ -0,0 +1,226 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+def parse(data):
+	lines = data.split('\n')
+	register = {
+		'A': int(lines[0].split(': ')[1]),
+		'B': int(lines[1].split(': ')[1]),
+		'C': int(lines[2].split(': ')[1]),
+	}
+	instructions = lines[4].split(': ')[1].split(',')
+	return register, [int(x) for x in instructions]
+
+split_data = parse
+completed = True
+raw_data = None # Not To be touched
+
+def part1(data):
+	register, instructions = data
+
+	def combo(oprand):
+		if 0 <= oprand <= 3:
+			return oprand
+		elif oprand == 4:
+			return register['A']
+		elif oprand == 5:
+			return register['B']
+		elif oprand == 6:
+			return register['C']
+		else:
+			raise "How are we executing a reserved value?"
+
+	pointer = 0
+	output = []
+	while pointer < len(instructions):
+		opcode = instructions[pointer]
+		oprand = instructions[pointer+1]
+
+		match opcode:
+			case 0:
+				register['A'] = int(register['A'] / (2**combo(oprand)))
+				pointer += 2
+			case 1:
+				register['B'] = register['B'] ^ oprand
+				pointer += 2
+			case 2:
+				register['B'] = combo(oprand) % 8
+				pointer += 2
+			case 3:
+				if register['A'] == 0:
+					pointer += 2
+				else:
+					pointer = oprand
+			case 4:
+				register['B'] = register['B'] ^ register['C']
+				pointer += 2
+			case 5:
+				output.append(str(combo(oprand) % 8))
+				pointer += 2
+			case 6:
+				register['B'] = int(register['A'] / (2**combo(oprand)))
+				pointer += 2
+			case 7:
+				register['C'] = int(register['A'] / (2**combo(oprand)))
+				pointer += 2
+			case default:
+				raise "ERR"
+
+	# print(pointer, output, register)
+	return ','.join(output)
+
+
+def compute(register, instructions):
+	pointer = 0
+	output = []
+	while pointer < len(instructions):
+		opcode = instructions[pointer]
+		oprand = instructions[pointer+1]
+		combo = ({4:register['A'],5:register['B'],6:register['C']}).get(oprand, oprand)
+
+		match opcode:
+			case 0:
+				register['A'] = int(register['A'] / (2**combo))
+				pointer += 2
+			case 1:
+				register['B'] = register['B'] ^ oprand
+				pointer += 2
+			case 2:
+				register['B'] = combo % 8
+				pointer += 2
+			case 3:
+				if register['A'] == 0:
+					pointer += 2
+				else:
+					pointer = oprand
+			case 4:
+				register['B'] = register['B'] ^ register['C']
+				pointer += 2
+			case 5:
+				output.append(combo % 8)
+				if len(output) > len(instructions) or output[-1] != instructions[len(output)-1]: return False
+				pointer += 2
+			case 6:
+				register['B'] = int(register['A'] / (2**combo))
+				pointer += 2
+			case 7:
+				register['C'] = int(register['A'] / (2**combo))
+				pointer += 2
+	
+	return output == instructions
+
+def part2(data):
+	"""
+	Forget about getting the answer by brute forcing it. 
+	It's not going to happen as the values we are looking for are too large
+	A much simpler method is backtracking. We can look at our program and notice a few things
+
+	My program:
+
+		B = A mod 8
+		B = B XOR 7
+		C = A / 2**B
+		A = A / 8
+		B = B XOR 7
+		B = B XOR C
+		OUT (B mod 8)
+		if A != 0 then jump 0
+
+
+	It ends with 3,0 aka if A != 0 then jump 0
+	and the only modification done to A is A = A / 2**3
+
+	Thus we know that our A should end in 0 for the program to halt which leaves us with a range of for A at the start [0*8, 1*8)
+	The range equals out to 0,1,2,3,4,5,6,7. `[]` brackets means inclusive and `()` brackets mean exclusive.
+
+	Running these possibilities through the program we can see that only 0 and 7 output a `0`.
+	As A can't with a 0 (as it would cause the program to halt in the previous cycle) we know the program will have to have a 7 at the start.
+	Thus in the last cycle we begin with a 7 to allow the program to halt and also give us the required `0` as output
+	Now we can extend the same logic backwards. Now we check the [7*8, (7+1)*8) interval for a 3 as output giving us 58 and 60.
+	Thus creating the interval [58*8,(58+1)*8) and [60*8, (60+1)*8) to check for the third last value and so on...
+
+	Summary:
+	last value: [0*8, 1*8) interval that outputs 0
+	2nd last value: [7*8, (7+1)*8) interval that outputs 3
+	3rd last value: [58*8,(58+1)*8) and [60*8, (60+1)*8) interval that outputs x
+	and so on...
+
+	As we are checking at max 8n possibilities for a single cycle where n averages at ~8 we should not have to look for much
+
+	Thus we get values of A which all end up producing the output we want. This may only work my input
+	"""
+
+	_, program = data
+
+	
+	def output(A):
+		return ((A % 8)^7^7 ^ int(A / 2**((A % 8) ^ 7))) % 8 # Simplified version 
+		print(A)
+		B = A % 8
+		B = A ^ 7
+		C = int(A / 2**B)
+		A = int(A / 8)
+		B = B ^ 7
+		B = B ^ C
+		return B % 8
+
+	growth = [0]
+	n = []
+	for out in program[::-1]:
+		growth = [x for a in growth for x in range(a*8, (a+1)*8) if x != 0 and output(x) == out]
+		n.append(len(growth))
+	return growth[0]
+
+"""
+Program: 2,4 1,7 7,5 0,3 1,7 4,1 5,5 3,0
+
+B = A mod 8
+B = B XOR 7 (7,6,5,4,3,2,1,0 as possibilities)
+C = A / 2**B
+A = A / 8
+B = B XOR 7 (0,1,2,3,4,5,6,7 as possibilities)
+B = B XOR C
+OUT B mod 8
+if A != 0 then jump 0
+
+```
+def check(A):
+  return ((A % 8) ^ int(A / 2**((A % 8) ^ 7))) % 8
+
+growth = [0]
+n = []
+for output in (2,4,1,7,7,5,0,3,1,7,4,1,5,5,3,0)[::-1]:
+	growth = [x for a in growth for x in range(a*8, (a+1)*8) if x != 0 and check(x) == output]
+	n.append(len(growth))
+
+growth[0]
+```
+
+
+
+The output is being done by B essentially. 
+We can manually back track the entire fucking thing...
+
+The only way to terminate the program is if A started less than 8
+We get 0 as output if A was 0 or 7 at the start.
+
+Knowing the logic of the program. We check [0*8, 1*8) and [7*8, 8*8) for output of 3.
+Sure enough the outputs 3, 58, and 60 all produce 3 which go on to produce 0.
+Thus we check for [3*8,4*8), [58*8, 59*8), and [60*8, 61*8) for production of 5.
+and so on and we are bound to find the value...
+
+Note: 0 can't be a possibility since it would mean that mean it would have terminated before...
+
+
+
+
+
+Thus the next values we look
+
+Hence A started out with <8
+B = 7 - A
+C = A / 2**(7-A) (0,1,3,7 as possible values)
+B = A
+
+
+"""