63 lines
1.7 KiB
Python
63 lines
1.7 KiB
Python
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def get_input(sample = False):
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with open("sample" if sample else "input", "r") as f:
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return [line.strip() for line in f.readlines()]
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def parse_instruction(instruction: str):
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return instruction[:3], int(instruction[4:])
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def cmd_n_to_instruction(cmd, n):
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return str(cmd) + " " + (f"+{n}" if n >= 0 else f"{n}")
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def instruction_results(cmd, n, i, acc):
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if cmd == "nop":
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return i + 1, acc
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elif cmd == "jmp":
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return i + n, acc
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elif cmd == "acc":
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return i + 1, acc + n
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def get_result(instructions: list, part = 1):
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acc = 0
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i = 0
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if part == 1:
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visited = set()
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while i not in visited:
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visited.add(i)
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i, acc = instruction_results(*parse_instruction(instructions[i]), i, acc)
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else:
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history = []
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revert = False
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switched_indices = set()
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while i < len(instructions):
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cmd, n = parse_instruction(instructions[i])
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if i in history:
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revert = True
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if not revert:
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history.append(i)
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i += n if cmd == "jmp" else 1
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else:
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if cmd in ["jmp", "nop"] and i not in switched_indices:
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instructions[i] = cmd_n_to_instruction("jmp" if cmd == "nop" else "nop", n)
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switched_indices.add(i)
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revert = False
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else:
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i = history[-1]
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history = history[:-1]
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for i in history:
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cmd, n = parse_instruction(instructions[i])
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if cmd == "acc":
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acc += n
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return acc
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if __name__ == "__main__":
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print(get_result(get_input(), part = 2))
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