Python: Day 4 solution

04/py/solution.py

@@ -0,0 +1,67 @@
+import operator
+from collections.abc import Callable
+from dataclasses import dataclass
+from pathlib import Path
+
+
+@dataclass(frozen=True, slots=True)
+class Range:
+    lower: int
+    upper: int
+
+    @classmethod
+    def from_pair(cls, s: str) -> "Range":
+        left, right = [int(num) for num in s.split("-")]
+        return cls(left, right)
+
+    @staticmethod
+    def _compare(a: "Range", b: "Range", _op: Callable[[bool, bool], bool]):
+        if _op(
+            b.lower <= a.lower <= b.upper,
+            b.lower <= a.upper <= b.upper,
+        ):
+            return True
+
+        if _op(
+            a.lower <= b.lower <= a.upper,
+            a.lower <= b.upper <= a.upper,
+        ):
+            return True
+
+        return False
+
+    def fully_contains(self, other: "Range") -> bool:
+        return Range._compare(self, other, operator.and_)
+
+    def overlaps(self, other: "Range") -> bool:
+        return Range._compare(self, other, operator.or_)
+
+
+def part1(data: str) -> int:
+    count = 0
+    for line in data.splitlines():
+        left, right = [Range.from_pair(s) for s in line.split(",")]
+        if left.fully_contains(right):
+            count += 1
+    return count
+
+
+def part2(data: str) -> int:
+    count = 0
+    for line in data.splitlines():
+        left, right = [Range.from_pair(s) for s in line.split(",")]
+        if left.overlaps(right):
+            count += 1
+    return count
+
+
+# Setup
+data = (Path(__file__).parents[1] / "input").read_text()
+
+# Problem solving - part 1
+result = part1(data)
+print(f"Part 1 solution: {result}")
+
+# Problem solving - part 2
+result = part2(data)
+print(f"Part 2 solution: {result}")

04/py/test_day04.py

@@ -0,0 +1,55 @@
+import pytest
+
+from solution import Range, part1, part2
+
+
+@pytest.fixture
+def example() -> str:
+    return """2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8"""
+
+
+@pytest.mark.parametrize(
+    "a,b,expected",
+    [
+        (Range(2, 4), Range(3, 4), True),
+        (Range(2, 4), Range(1, 4), True),
+        (Range(2, 4), Range(2, 4), True),
+        (Range(4, 4), Range(3, 4), True),
+        (Range(2, 4), Range(3, 5), False),
+        (Range(4, 4), Range(3, 3), False),
+    ],
+)
+def test_range_fully_contains(a: Range, b: Range, expected: bool) -> None:
+    assert a.fully_contains(b) == expected
+    assert b.fully_contains(a) == expected
+
+
+@pytest.mark.parametrize(
+    "a,b,expected",
+    [
+        (Range(5, 7), Range(7, 9), True),
+        (Range(2, 8), Range(3, 7), True),
+        (Range(6, 6), Range(4, 6), True),
+        (Range(2, 6), Range(4, 8), True),
+        (Range(5, 7), Range(8, 9), False),
+        (Range(2, 3), Range(5, 7), False),
+        (Range(6, 6), Range(4, 5), False),
+        (Range(2, 2), Range(4, 4), False),
+    ],
+)
+def test_range_overlaps(a: Range, b: Range, expected: bool) -> None:
+    assert a.overlaps(b) == expected
+    assert b.overlaps(a) == expected
+
+
+def test_part1(example: str) -> None:
+    assert part1(example) == 2
+
+
+def test_part2(example: str) -> None:
+    assert part2(example) == 4