AoC 2020: day8

Signed-off-by: Ettore Dreucci <ettore.dreucci@gmail.com>

2020-python/solutions/day_8.py

@@ -0,0 +1,106 @@
+"""AOC 2020 Day 8"""
+
+import pathlib
+import time
+
+TEST_INPUT = """nop +0
+acc +1
+jmp +4
+acc +3
+jmp -3
+acc -99
+acc +1
+jmp -4
+acc +6"""
+
+class Instruction:
+    """Instruction class hold an operation, an argument and an execution counter"""
+    op = None
+    arg = None
+
+    def __init__(self, op, arg):
+        self.op = op
+        self.arg = arg
+
+def read_input(input_path: str) -> str:
+    """take input file path and return a str with the file's content"""
+    with open(input_path, 'r') as input_file:
+        input_data = input_file.read().strip()
+        return input_data
+
+def extract(input_data: str) -> list:
+    """take input data and return the appropriate data structure"""
+    instructions = list()
+    for instruction in input_data.split('\n'):
+        op, arg = instruction.split(' ')
+        arg = int(arg)
+        assert op in ('acc', 'jmp', 'nop')
+        instructions.append(Instruction(op, arg))
+    return instructions
+
+def run(entries: list) -> (int, bool):
+    """run instructions"""
+    instruction_counter = 0
+    prev_instruction_counter = 0
+    accumulator = 0
+    exec_counter = [0]*len(entries)
+    while instruction_counter < len(entries):
+        prev_instruction_counter = instruction_counter
+        instruction = entries[instruction_counter]
+
+        if exec_counter[instruction_counter] != 0:
+            return accumulator, False
+
+        if instruction.op == 'nop':
+            instruction_counter += 1
+        elif instruction.op == 'acc':
+            accumulator += instruction.arg
+            instruction_counter += 1
+        elif instruction.op == 'jmp':
+            instruction_counter += instruction.arg
+        else:
+            raise ValueError('Invalid instruction operation %s' % instruction.op)
+
+        exec_counter[prev_instruction_counter] += 1
+
+    return accumulator, True
+
+def part1(entries: list) -> int:
+    """part1 solver"""
+    return run(entries)[0]
+
+def part2(entries: list) -> int:
+    """part2 solver"""
+    for instruction in entries:
+        if instruction.op == 'acc':
+            continue
+        original_instruction = instruction.op
+        instruction.op = 'jmp' if instruction.op == 'nop' else 'nop'
+        accumulator, success = run(entries)
+        if success:
+            return accumulator
+        instruction.op = original_instruction
+
+def test_input_day_8():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries) == 5
+    assert part2(entries) == 8
+
+def test_bench_day_8(benchmark):
+    """pytest-benchmark function"""
+    benchmark(main)
+
+def main():
+    """main function"""
+    input_path = str(pathlib.Path(__file__).resolve().parent.parent) + "/inputs/" + str(pathlib.Path(__file__).stem)
+    start_time = time.time()
+    input_data = read_input(input_path)
+    entries = extract(input_data)
+    print("Part 1: %d" % part1(entries))
+    print("Part 2: %d" % part2(entries))
+    end_time = time.time()
+    print("Execution time: %f" % (end_time-start_time))
+
+if __name__ == "__main__":
+    main()