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4bad7e1de4
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6eb1814105
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#!/usr/bin/env python
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import dataclasses
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import enum
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import sys
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@dataclasses.dataclass
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class Registers:
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reg_a: int
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reg_b: int
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reg_c: int
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class Instruction(enum.IntEnum):
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ADV = 0
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BXL = 1
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BST = 2
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JNZ = 3
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BXC = 4
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OUT = 5
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BDV = 6
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CDV = 7
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@dataclasses.dataclass
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class Computer:
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registers: Registers
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program: list[int]
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ip: int = 0
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def _resolve_combo_operand(self, operand: int) -> int:
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assert operand != 7 # Sanity check
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if 0 <= operand <= 3:
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return operand
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if operand == 4:
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return self.registers.reg_a
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if operand == 5:
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return self.registers.reg_b
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if operand == 6:
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return self.registers.reg_c
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assert False # Sanity check
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# Returns False if the computer is halted
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# `output` is an out parameter
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def step(self, output: list[int]) -> bool:
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# NOTE: also accounting for operand in overflow check here
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if (self.ip + 1) >= len(self.program):
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return False
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instr, literal_operand = (
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Instruction(self.program[self.ip]),
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self.program[self.ip + 1],
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)
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combo_operand = self._resolve_combo_operand(literal_operand)
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ip_delta = 2
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match instr:
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case Instruction.ADV:
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self.registers.reg_a //= 2**combo_operand
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case Instruction.BXL:
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self.registers.reg_b ^= literal_operand
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case Instruction.BST:
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self.registers.reg_b = combo_operand % 8
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case Instruction.JNZ:
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if self.registers.reg_a != 0:
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self.ip = literal_operand
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ip_delta = 0
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case Instruction.BXC:
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self.registers.reg_b ^= self.registers.reg_c
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case Instruction.OUT:
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output.append(combo_operand % 8)
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case Instruction.BDV:
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self.registers.reg_b = self.registers.reg_a // 2**combo_operand
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case Instruction.CDV:
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self.registers.reg_c = self.registers.reg_a // 2**combo_operand
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self.ip += ip_delta
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return True
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def solve(input: str) -> str:
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def parse_registers(input: list[str]) -> Registers:
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def parse_register(input: str) -> int:
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return int(input.split(": ")[1])
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return Registers(*map(parse_register, input))
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def parse(input: str) -> Computer:
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registers, program_str = input.split("\n\n")
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program = list(map(int, program_str.removeprefix("Program: ").split(",")))
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return Computer(parse_registers(registers.splitlines()), program)
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computer = parse(input)
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output: list[int] = []
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while computer.step(output):
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pass
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return ",".join(str(n) for n in output)
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def main() -> None:
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input = sys.stdin.read()
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print(solve(input))
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if __name__ == "__main__":
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main()
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@ -1,5 +0,0 @@
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Register A: 30886132
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Register B: 0
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Register C: 0
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Program: 2,4,1,1,7,5,0,3,1,4,4,4,5,5,3,0
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@ -1,135 +0,0 @@
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#!/usr/bin/env python
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import copy
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import dataclasses
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import enum
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import sys
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@dataclasses.dataclass
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class Registers:
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reg_a: int
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reg_b: int
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reg_c: int
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class Instruction(enum.IntEnum):
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ADV = 0
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BXL = 1
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BST = 2
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JNZ = 3
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BXC = 4
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OUT = 5
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BDV = 6
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CDV = 7
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@dataclasses.dataclass
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class Computer:
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registers: Registers
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program: list[int]
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ip: int = 0
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def _resolve_combo_operand(self, operand: int) -> int:
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assert operand != 7 # Sanity check
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if 0 <= operand <= 3:
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return operand
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if operand == 4:
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return self.registers.reg_a
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if operand == 5:
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return self.registers.reg_b
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if operand == 6:
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return self.registers.reg_c
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assert False # Sanity check
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# Returns False if the computer is halted
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# `output` is an out parameter
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def step(self, output: list[int]) -> bool:
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# NOTE: also accounting for operand in overflow check here
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if (self.ip + 1) >= len(self.program):
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return False
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instr, literal_operand = (
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Instruction(self.program[self.ip]),
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self.program[self.ip + 1],
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)
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combo_operand = self._resolve_combo_operand(literal_operand)
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ip_delta = 2
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match instr:
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case Instruction.ADV:
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self.registers.reg_a //= 2**combo_operand
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case Instruction.BXL:
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self.registers.reg_b ^= literal_operand
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case Instruction.BST:
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self.registers.reg_b = combo_operand % 8
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case Instruction.JNZ:
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if self.registers.reg_a != 0:
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self.ip = literal_operand
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ip_delta = 0
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case Instruction.BXC:
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self.registers.reg_b ^= self.registers.reg_c
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case Instruction.OUT:
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output.append(combo_operand % 8)
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case Instruction.BDV:
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self.registers.reg_b = self.registers.reg_a // 2**combo_operand
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case Instruction.CDV:
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self.registers.reg_c = self.registers.reg_a // 2**combo_operand
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self.ip += ip_delta
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return True
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def solve(input: str) -> int:
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def parse_registers(input: list[str]) -> Registers:
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def parse_register(input: str) -> int:
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return int(input.split(": ")[1])
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return Registers(*map(parse_register, input))
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def parse(input: str) -> Computer:
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registers, program_str = input.split("\n\n")
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program = list(map(int, program_str.removeprefix("Program: ").split(",")))
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return Computer(parse_registers(registers.splitlines()), program)
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# Rely on the shape of the input, which reads 3 bits of reg_a at a time
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def find_quine(computer: Computer) -> int:
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def is_quine(a: int, n_outputs: int) -> bool:
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if n_outputs == 0:
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return True
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tmp = copy.deepcopy(computer)
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tmp.registers.reg_a = a
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output: list[int] = []
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while tmp.step(output):
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pass
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return output[-n_outputs:] == computer.program[-n_outputs:]
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def helper(a: int, n_outputs: int) -> int | None:
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# If not a quine of the correct length, abandon this candidate
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if not is_quine(a, n_outputs):
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return None
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# If we've found all digits, return the candidate
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if n_outputs == len(computer.program):
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return a
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# Try to find a longer quine, starting from this candidate
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for next_a in range(a * 8, a * 8 + 8):
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# We found a full quine, guaranteed to be the smallest value
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if (res := helper(next_a, n_outputs + 1)) is not None:
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return res
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return None
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res = helper(0, 0)
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assert res is not None # Sanity check
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return res
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computer = parse(input)
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return find_quine(computer)
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def main() -> None:
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input = sys.stdin.read()
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print(solve(input))
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if __name__ == "__main__":
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main()
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@ -1,5 +0,0 @@
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Register A: 30886132
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Register B: 0
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Register C: 0
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Program: 2,4,1,1,7,5,0,3,1,4,4,4,5,5,3,0
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