AoC 2020: day9

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

2020-python/solutions/day_9.py

@@ -0,0 +1,85 @@
+"""AOC 2020 Day 9"""
+
+import pathlib
+import time
+import itertools
+
+TEST_INPUT = """35
+20
+15
+25
+47
+40
+62
+55
+65
+95
+102
+117
+150
+182
+127
+219
+299
+277
+309
+576"""
+
+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"""
+    entries = list()
+    for entry in input_data.split('\n'):
+        entries.append(int(entry))
+    return entries
+
+def part1(entries: list, preamble_length: int) -> int:
+    """part1 solver"""
+    for index, entry in enumerate(entries[preamble_length:]):
+        preamble = entries[index:index+preamble_length]
+        if entry not in [i+j for i, j in itertools.combinations(preamble, 2)]:
+            return entry
+    return None
+
+def part2(entries: list, invalid_number: int) -> int:
+    """part2 solver"""
+    for index, _ in enumerate(entries):
+        test_set = [entries[index]]
+        test_set_len = 1
+        while test_set_len < len(entries) - index:
+            test_set.append(entries[index+test_set_len])
+            test_set_len += 1
+
+            if sum(test_set) == invalid_number:
+                return min(test_set) + max(test_set)
+    return None
+
+def test_input_day_9():
+    """pytest testing function"""
+    entries = extract(TEST_INPUT)
+    assert part1(entries, 5) == 127
+    assert part2(entries, 127) == 62
+
+def test_bench_day_9(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)
+    invalid_number = part1(entries, 25)
+    print("Part 1: %d" % invalid_number)
+    print("Part 2: %d" % part2(entries, invalid_number))
+    end_time = time.time()
+    print("Execution time: %f" % (end_time-start_time))
+
+if __name__ == "__main__":
+    main()