diff --git a/puzzles/1.py b/puzzles/1.py
index 2887847..7020b20 100644
--- a/puzzles/1.py
+++ b/puzzles/1.py
@@ -1,33 +1,48 @@
 from collections import Counter
+from textwrap import dedent
+from typing import override
+from unittest import TestCase
 
-test_input = """
-3   4
-4   3
-2   5
-1   3
-3   9
-3   3
-"""
-
-test_solution_p1 = 11
-test_solution_p2 = 31
+from puzzles._solver import Solver
 
 
-def solve_p1(puzzle_input: str) -> int:
-    list1, list2 = _parse_lists(puzzle_input)
-    pairs = zip(sorted(list1), sorted(list2))
-    distances = (abs(pair[0] - pair[1]) for pair in pairs)
-    return sum(distances)
+class DayOneSolver(Solver):
+    list1: list[int]
+    list2: list[int]
+
+    @override
+    def __init__(self, puzzle_input: str):
+        lines = (line.partition("   ") for line in puzzle_input.strip().split("\n"))
+        list1, list2 = zip(*((int(line[0]), int(line[2])) for line in lines))
+        self.list1 = list(list1)
+        self.list2 = list(list2)
+
+    @override
+    def solve_p1(self) -> int:
+        minimum_pairs = zip(sorted(self.list1), sorted(self.list2))
+        return sum(abs(a - b) for a, b in minimum_pairs)
+
+    @override
+    def solve_p2(self) -> int:
+        occurrences = Counter(self.list2)
+        return sum(value * occurrences.get(value, 0) for value in self.list1)
 
 
-def solve_p2(puzzle_input: str) -> int:
-    list1, list2 = _parse_lists(puzzle_input)
-    occurrences = Counter(list2)
-    similarities = (value * occurrences.get(value, 0) for value in list1)
-    return sum(similarities)
-
-
-def _parse_lists(puzzle_input: str) -> tuple[list[int], list[int]]:
-    lines = (line.partition("   ") for line in puzzle_input.strip().split("\n"))
-    list1, list2 = zip(*((int(line[0]), int(line[2])) for line in lines))
-    return list1, list2
+class TestDayOneSolver(TestCase):
+    def test(self):
+        solver = DayOneSolver(
+            dedent(
+                """
+                3   4
+                4   3
+                2   5
+                1   3
+                3   9
+                3   3
+                """
+            )
+        )
+        self.assertListEqual(solver.list1, [3, 4, 2, 1, 3, 3])
+        self.assertListEqual(solver.list2, [4, 3, 5, 3, 9, 3])
+        self.assertEqual(solver.solve_p1(), 11)
+        self.assertEqual(solver.solve_p2(), 31)
diff --git a/puzzles/2.py b/puzzles/2.py
index 3e8ba4a..0e84b92 100644
--- a/puzzles/2.py
+++ b/puzzles/2.py
@@ -1,63 +1,88 @@
-from itertools import islice
-from typing import Iterator
+from dataclasses import dataclass
+from functools import cached_property
+from itertools import pairwise
+from textwrap import dedent
+from typing import Iterator, override
+from unittest import TestCase
 
 from more_itertools import ilen
 
-test_input = """
-7 6 4 2 1
-1 2 7 8 9
-9 7 6 2 1
-1 3 2 4 5
-8 6 4 4 1
-1 3 6 7 9
-"""
-
-test_solution_p1 = 2
-test_solution_p2 = 4
+from puzzles._solver import Solver
 
 
-def solve_p1(puzzle_input: str) -> int:
-    reports = _parse_reports(puzzle_input)
-    delta_reports = (_deltas(report) for report in reports)
-    safe_delta_reports = filter(_is_gradual_monotonic, delta_reports)
-    return ilen(safe_delta_reports)
+@dataclass
+class Report:
+    levels: tuple[int, ...]
+
+    @cached_property
+    def deltas(self) -> tuple[int, ...]:
+        return tuple(b - a for a, b in pairwise(self.levels))
+
+    def is_gradual_monotonic(self) -> bool:
+        sign = 1 if self.deltas[0] > 0 else -1
+        return all(
+            delta != 0 and delta / abs(delta) == sign and abs(delta) < 4
+            for delta in self.deltas
+        )
+
+    def permute_dampened_variations(self) -> Iterator["Report"]:
+        return (
+            Report(self.levels[:i] + self.levels[i + 1 :])
+            for i in range(0, len(self.levels) + 1)
+        )
 
 
-def solve_p2(puzzle_input: str) -> int:
-    reports = _parse_reports(puzzle_input)
-    dampened_report_collections = (_dampen_permutations(report) for report in reports)
-    delta_report_collections = (
-        (_deltas(report) for report in report_collection)
-        for report_collection in dampened_report_collections
-    )
-    safe_report_collections = filter(
-        lambda delta_report_collection: any(
-            _is_gradual_monotonic(delta_report)
-            for delta_report in delta_report_collection
-        ),
-        delta_report_collections,
-    )
-    return ilen(safe_report_collections)
+class DayTwoSolver(Solver):
+    reports: list[Report]
+
+    @override
+    def __init__(self, puzzle_input: str):
+        self.reports = list(
+            Report(tuple(int(level) for level in line.split(" ")))
+            for line in puzzle_input.strip().splitlines()
+        )
+
+    @override
+    def solve_p1(self) -> int:
+        safe_reports = filter(Report.is_gradual_monotonic, self.reports)
+        return ilen(safe_reports)
+
+    @override
+    def solve_p2(self) -> int:
+        safe_reports = filter(
+            lambda report: any(
+                report_variation.is_gradual_monotonic()
+                for report_variation in report.permute_dampened_variations()
+            ),
+            self.reports,
+        )
+        return ilen(safe_reports)
 
 
-def _parse_reports(puzzle_input: str) -> Iterator[tuple[int, ...]]:
-    lines = puzzle_input.strip().splitlines()
-    return (tuple(int(level) for level in line.split(" ")) for line in lines)
-
-
-def _deltas(report: tuple[int, ...]) -> tuple[int, ...]:
-    pairs = zip(report, islice(report, 1, None))
-    return tuple(b - a for a, b in pairs)
-
-
-def _is_gradual_monotonic(delta_report: tuple[int]) -> bool:
-    sign = 1 if delta_report[0] > 0 else -1
-    return all(
-        delta != 0 and delta / abs(delta) == sign and abs(delta) < 4
-        for delta in delta_report
-    )
-
-
-def _dampen_permutations(report: tuple[int, ...]) -> Iterator[tuple[int, ...]]:
-    yield report
-    yield from (report[:i] + report[i + 1 :] for i in range(0, len(report)))
+class TestDayNSolver(TestCase):
+    def test(self):
+        solver = DayTwoSolver(
+            dedent(
+                """
+                7 6 4 2 1
+                1 2 7 8 9
+                9 7 6 2 1
+                1 3 2 4 5
+                8 6 4 4 1
+                1 3 6 7 9
+                """
+            )
+        )
+        self.assertListEqual(
+            solver.reports,
+            [
+                Report((7, 6, 4, 2, 1)),
+                Report((1, 2, 7, 8, 9)),
+                Report((9, 7, 6, 2, 1)),
+                Report((1, 3, 2, 4, 5)),
+                Report((8, 6, 4, 4, 1)),
+                Report((1, 3, 6, 7, 9)),
+            ],
+        )
+        self.assertEqual(solver.solve_p1(), 2)
+        self.assertEqual(solver.solve_p2(), 4)
diff --git a/puzzles/3.py b/puzzles/3.py
index d3befd8..888beff 100644
--- a/puzzles/3.py
+++ b/puzzles/3.py
@@ -1,40 +1,58 @@
 import re
-from functools import reduce
+from typing import Literal, override
+from unittest import TestCase
 
-test_input_p1 = """
-xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))
-"""
-
-test_input_p2 = """
-xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))
-"""
-
-test_solution_p1 = 161
-test_solution_p2 = 48
-
-instruction_pattern = re.compile(r"mul\((\d+),(\d+)\)|(do(?:n't)?)\(\)")
+from puzzles._solver import Solver
 
 
-def solve_p1(puzzle_input: str) -> int:
-    instructions = (
-        tuple(map(int, match[:2]))
-        for match in instruction_pattern.findall(puzzle_input)
-        if match[0]
-    )
-    return sum(a * b for a, b in instructions)
+class DayThreeSolver(Solver):
+    memory: tuple[int, int] | Literal["do", "don't"]
+
+    @override
+    def __init__(self, puzzle_input: str):
+        matches = re.findall(r"mul\((\d+),(\d+)\)|(do(?:n't)?)\(\)", puzzle_input)
+        self.memory = tuple(
+            (int(a), int(b)) if a else enable_flag for a, b, enable_flag in matches
+        )
+
+    @override
+    def solve_p1(self) -> int:
+        total = 0
+
+        for match in self.memory:
+            match match:
+                case a, b:
+                    total += a * b
+
+        return total
+
+    @override
+    def solve_p2(self) -> int:
+        total = 0
+        enabled = True
+
+        for match in self.memory:
+            match match:
+                case "do":
+                    enabled = True
+                case "don't":
+                    enabled = False
+                case a, b:
+                    if enabled:
+                        total += a * b
+
+        return total
 
 
-def solve_p2(puzzle_input: str) -> int:
-    instructions = (
-        match[2] or tuple(map(int, match[:2]))
-        for match in instruction_pattern.findall(puzzle_input)
-    )
-    return reduce(
-        lambda a, i: (
-            (1 if i == "do" else 0, a[1])
-            if isinstance(i, str)
-            else (a[0], a[1] + a[0] * i[0] * i[1])
-        ),
-        instructions,
-        (1, 0),
-    )[1]
+class TestDayThreeSolver(TestCase):
+    def test_solve_p1(self):
+        solver = DayThreeSolver(
+            "xmul(2,4)%&mul[3,7]!@^do_not_mul(5,5)+mul(32,64]then(mul(11,8)mul(8,5))\n"
+        )
+        self.assertEqual(solver.solve_p1(), 161)
+
+    def test_solve_p2(self):
+        solver = DayThreeSolver(
+            "xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))\n"
+        )
+        self.assertEqual(solver.solve_p2(), 48)
diff --git a/puzzles/4.py b/puzzles/4.py
index 0291751..371babe 100644
--- a/puzzles/4.py
+++ b/puzzles/4.py
@@ -1,83 +1,90 @@
-from typing import Iterator
+from textwrap import dedent
+from typing import Iterator, override
+from unittest import TestCase
 
-test_input = """
-MMMSXXMASM
-MSAMXMSMSA
-AMXSXMAAMM
-MSAMASMSMX
-XMASAMXAMM
-XXAMMXXAMA
-SMSMSASXSS
-SAXAMASAAA
-MAMMMXMMMM
-MXMXAXMASX
-"""
+from more_itertools import sliding_window
 
-test_solution_p1 = 18
-test_solution_p2 = 9
+from puzzles._solver import Solver
+
+Line = tuple[str, ...]
+Grid = tuple[Line, ...]
 
 
-def solve_p1(puzzle_input: str) -> int:
-    word_grid = _parse_world_grid(puzzle_input)
-    return sum(_count_xmas(line) for line in _scan_word_grid(word_grid))
+class DayFourSolver(Solver):
+    grid: Grid
 
+    @override
+    def __init__(self, puzzle_input: str):
+        self.grid = tuple(tuple(row) for row in puzzle_input.strip().splitlines())
 
-def solve_p2(puzzle_input: str) -> int:
-    word_grid = _parse_world_grid(puzzle_input)
-    squares = _three_squares(word_grid)
-    return sum(1 for square in squares if _has_cross_mas(square))
-
-
-def _parse_world_grid(puzzle_input: str) -> tuple[tuple[str, ...], ...]:
-    return tuple(tuple(row) for row in puzzle_input.strip().splitlines())
-
-
-def _scan_word_grid(
-    char_grid: tuple[tuple[str, ...], ...]
-) -> Iterator[tuple[str, ...]]:
-    yield from (row for row in char_grid)
-    yield from (tuple(col) for col in zip(*char_grid))
-    yield from (
-        _diagonal(char_grid, i) for i in range(-len(char_grid) + 1, len(char_grid[0]))
-    )
-    yield from (
-        _diagonal(tuple(reversed(char_grid)), i)
-        for i in range(-len(char_grid) + 1, len(char_grid[0]))
-    )
-
-
-def _diagonal(grid: tuple[tuple[str, ...], ...], offset=0) -> tuple[str, ...]:
-    return tuple(
-        grid[i][i + offset] for i in range(len(grid)) if 0 <= i + offset < len(grid)
-    )
-
-
-def _count_xmas(line: tuple[str, ...]) -> int:
-    return sum(
-        1
-        for i in range(len(line) - 3)
-        if line[i : i + 4] in (("X", "M", "A", "S"), ("S", "A", "M", "X"))
-    )
-
-
-ThreeSquare = tuple[tuple[str, str, str], tuple[str, str, str], tuple[str, str, str]]
-
-
-def _three_squares(word_grid: tuple[tuple[str, ...], ...]) -> Iterator[ThreeSquare]:
-    yield from (
-        (
-            word_grid[i][j : j + 3],
-            word_grid[i + 1][j : j + 3],
-            word_grid[i + 2][j : j + 3],
+    @override
+    def solve_p1(self) -> int:
+        targets = (("X", "M", "A", "S"), ("S", "A", "M", "X"))
+        return sum(
+            1
+            for line in self.scan_lines()
+            for window in sliding_window(line, 4)
+            if window in targets
+        )
+
+    @override
+    def solve_p2(self) -> int:
+        targets = (("M", "A", "S"), ("S", "A", "M"))
+        return sum(
+            1
+            for square in self.scan_squares(3)
+            if (square[0][0], square[1][1], square[2][2]) in targets
+            and (square[0][2], square[1][1], square[2][0]) in targets
+        )
+
+    def scan_lines(self) -> Iterator[Line]:
+        yield from self.grid
+        for col in zip(*self.grid):
+            yield tuple(col)
+        for i in range(-len(self.grid) + 1, len(self.grid[0])):
+            yield self.diagonal(i)
+            yield self.diagonal(i, inverse=True)
+
+    def scan_squares(self, size=3) -> Iterator[Grid]:
+        yield from (
+            (
+                self.grid[i][j : j + size],
+                self.grid[i + 1][j : j + size],
+                self.grid[i + 2][j : j + size],
+            )
+            for i in range(len(self.grid) - size + 1)
+            for j in range(len(self.grid[0]) - size + 1)
+        )
+
+    def diagonal(self, offset=0, inverse=False) -> Line:
+        return tuple(
+            self.grid[i][len(self.grid[0]) - i - offset - 1 if inverse else i + offset]
+            for i in range(len(self.grid))
+            if 0 <= i + offset < len(self.grid)
         )
-        for i in range(len(word_grid) - 2)
-        for j in range(len(word_grid[0]) - 2)
-    )
 
 
-def _has_cross_mas(square: ThreeSquare):
-    diag_1 = (square[0][0], square[1][1], square[2][2])
-    diag_2 = (square[0][2], square[1][1], square[2][0])
-    return (diag_1 == ("M", "A", "S") or diag_1 == ("S", "A", "M")) and (
-        diag_2 == ("M", "A", "S") or diag_2 == ("S", "A", "M")
-    )
+class TestDayFourSolver(TestCase):
+    def test(self):
+        solver = DayFourSolver(
+            dedent(
+                """
+                MMMSXXMASM
+                MSAMXMSMSA
+                AMXSXMAAMM
+                MSAMASMSMX
+                XMASAMXAMM
+                XXAMMXXAMA
+                SMSMSASXSS
+                SAXAMASAAA
+                MAMMMXMMMM
+                MXMXAXMASX
+                """
+            )
+        )
+        self.assertEqual(
+            solver.grid[0],
+            ("M", "M", "M", "S", "X", "X", "M", "A", "S", "M"),
+        )
+        self.assertEqual(solver.solve_p1(), 18)
+        self.assertEqual(solver.solve_p2(), 9)
diff --git a/puzzles/5.py b/puzzles/5.py
index 34d2e65..027aa62 100644
--- a/puzzles/5.py
+++ b/puzzles/5.py
@@ -1,110 +1,116 @@
-from typing import Iterator
+from textwrap import dedent
+from typing import Iterator, override
+from unittest import TestCase
 
-test_input = """
-47|53
-97|13
-97|61
-97|47
-75|29
-61|13
-75|53
-29|13
-97|29
-53|29
-61|53
-97|53
-61|29
-47|13
-75|47
-97|75
-47|61
-75|61
-47|29
-75|13
-53|13
+from puzzles._solver import Solver
 
-75,47,61,53,29
-97,61,53,29,13
-75,29,13
-75,97,47,61,53
-61,13,29
-97,13,75,29,47
-"""
-
-test_solution_p1 = 143
-test_solution_p2 = 123
-
-
-def solve_p1(puzzle_input: str) -> int:
-    rules, updates = _parse_rules_and_updates(puzzle_input)
-    return sum(
-        update[len(update) // 2]
-        for update in updates
-        if _is_correctly_ordered(rules, update)
-    )
-
-
-def solve_p2(puzzle_input: str) -> int:
-    rules, updates = _parse_rules_and_updates(puzzle_input)
-    corrected_updates = (
-        _fix_update(rules, update)
-        for update in updates
-        if not _is_correctly_ordered(rules, update)
-    )
-    return sum(update[len(update) // 2] for update in corrected_updates)
-
-
-OrderingRules = dict[int, set[int]]
 Update = tuple[int, ...]
 
 
-def _parse_rules_and_updates(
-    puzzle_input: str,
-) -> tuple[OrderingRules, Iterator[Update]]:
-    ordering_rules, _, updates = puzzle_input.partition("\n\n")
+class DayFiveSolver(Solver):
+    ordering_rules: dict[int, set[int]]
+    updates: list[Update]
 
-    rules: OrderingRules = {}
-    for line in ordering_rules.strip().split("\n"):
-        a, _, b = line.partition("|")
-        a, b = int(a), int(b)
-        if b not in rules:
-            rules[b] = set()
-        rules[b].add(a)
+    @override
+    def __init__(self, puzzle_input: str):
+        ordering_rules_input, _, updates_input = puzzle_input.partition("\n\n")
+        self.ordering_rules = {}
 
-    return (
-        rules,
-        (tuple(map(int, line.split(","))) for line in updates.strip().split("\n")),
-    )
+        for line in ordering_rules_input.strip().split("\n"):
+            a, _, b = line.partition("|")
+            a, b = int(a), int(b)
+            if b not in self.ordering_rules:
+                self.ordering_rules[b] = set()
+            self.ordering_rules[b].add(a)
+
+        self.updates = [
+            tuple(map(int, line.split(",")))
+            for line in updates_input.strip().split("\n")
+        ]
+
+    @override
+    def solve_p1(self) -> int:
+        return sum(
+            update[len(update) // 2]
+            for update in self.updates
+            if self.is_correctly_ordered(update)
+        )
+
+    @override
+    def solve_p2(self) -> int:
+        return sum(
+            self.fix_update(update)[len(update) // 2]
+            for update in self.updates
+            if not self.is_correctly_ordered(update)
+        )
+
+    def is_correctly_ordered(self, update: Update) -> bool:
+        contains = set(update)
+        seen = set()
+
+        for i in update:
+            for j in self.ordering_rules.get(i, ()):
+                if j in contains and j not in seen:
+                    return False
+            seen.add(i)
+
+        return True
+
+    def fix_update(self, update: Update) -> Update:
+        contains = set(update)
+        seen = set()
+
+        fixed_update = list()
+
+        def fix_item(i):
+            for j in self.ordering_rules.get(i, ()):
+                if j in contains and j not in seen:
+                    fix_item(j)
+            fixed_update.append(i)
+            seen.add(i)
+
+        for i in update:
+            if i not in seen:
+                fix_item(i)
+
+        return tuple(fixed_update)
 
 
-def _is_correctly_ordered(rules: OrderingRules, update: Update) -> bool:
-    contains = set(update)
-    seen = set()
+class TestDayFiveSolver(TestCase):
+    def test(self):
+        solver = DayFiveSolver(
+            dedent(
+                """
+                47|53
+                97|13
+                97|61
+                97|47
+                75|29
+                61|13
+                75|53
+                29|13
+                97|29
+                53|29
+                61|53
+                97|53
+                61|29
+                47|13
+                75|47
+                97|75
+                47|61
+                75|61
+                47|29
+                75|13
+                53|13
 
-    for i in update:
-        for j in rules.get(i, ()):
-            if j in contains and j not in seen:
-                return False
-        seen.add(i)
-
-    return True
-
-
-def _fix_update(rules: OrderingRules, update: Update) -> Update:
-    contains = set(update)
-    seen = set()
-
-    fixed_update = list()
-
-    def _fix_item(i):
-        for j in rules.get(i, ()):
-            if j in contains and j not in seen:
-                _fix_item(j)
-        fixed_update.append(i)
-        seen.add(i)
-
-    for i in update:
-        if i not in seen:
-            _fix_item(i)
-
-    return tuple(fixed_update)
+                75,47,61,53,29
+                97,61,53,29,13
+                75,29,13
+                75,97,47,61,53
+                61,13,29
+                97,13,75,29,47
+                """
+            )
+        )
+        self.assertEqual(solver.solve_p1(), 143)
+        self.assertEqual(solver.solve_p2(), 123)
diff --git a/puzzles/6.py b/puzzles/6.py
index 4c71977..2a63175 100644
--- a/puzzles/6.py
+++ b/puzzles/6.py
@@ -1,122 +1,160 @@
-from typing import NamedTuple
+from dataclasses import dataclass
+from textwrap import dedent
+from typing import Literal, NamedTuple, get_args, override
+from unittest import TestCase
 
-test_input = """
-....#.....
-.........#
-..........
-..#.......
-.......#..
-..........
-.#..^.....
-........#.
-#.........
-......#...
-"""
+from puzzles._solver import Solver
 
-test_solution_p1 = 41
-test_solution_p2 = 6
-
-
-def solve_p1(puzzle_input: str) -> int:
-    map_info = _parse_map(puzzle_input)
-    traversal_analysis = _traverse_map(map_info)
-    unique_locations = set((a, b) for a, b, _ in traversal_analysis.visited)
-    return len(unique_locations)
-
-
-def solve_p2(puzzle_input: str) -> int:
-    map_info = _parse_map(puzzle_input)
-    added_obstacles_candidates = set()
-
-    for i, line in enumerate(map_info.map):
-        for j, cell in enumerate(line):
-            if not cell:
-                map_info.map[i][j] = True
-                if _traverse_map(map_info).stuck:
-                    added_obstacles_candidates.add((i, j))
-                map_info.map[i][j] = False
-
-    # Remove guard location from candidates
-    added_obstacles_candidates.discard((map_info.guard[:2]))
-
-    return len(added_obstacles_candidates)
-
-
-class MapInfo(NamedTuple):
-    map: list[list[bool]]
-    guard: tuple[int, int, str]
-
-
-def _parse_map(puzzle_input: str) -> MapInfo:
-    puzzle_map = []
-    guard = None
-
-    for x, line in enumerate(puzzle_input.strip().split("\n")):
-        if not line:
-            continue
-        line_list = list()
-        for y, cell in enumerate(line):
-            if cell in "^v<>":
-                guard = (x, y, cell)
-            line_list.append(cell == "#")
-        puzzle_map.append(line_list)
-
-    assert guard is not None, "Guard not found in map"
-    assert all(
-        len(line) == len(puzzle_map[0]) for line in puzzle_map
-    ), "Map is not rectangular"
-
-    return MapInfo(puzzle_map, guard)
-
-
-class TraversalAnalysis(NamedTuple):
-    visited: set[tuple[int, int]]
-    stuck: bool
-
-
-_rotation_map = {
-    "^": ">",
-    "v": "<",
-    "<": "^",
-    ">": "v",
+direction_map = {
+    "^": (-1, 0),
+    "v": (1, 0),
+    "<": (0, -1),
+    ">": (0, 1),
 }
 
 
-def _traverse_map(map_info: MapInfo) -> TraversalAnalysis:
-    x, y, direction = map_info.guard
-    visited = set()
-    visited.add((x, y, direction))
+class GuardPosition(NamedTuple):
+    x: int
+    y: int
+    direction: tuple[int, int]
 
-    while True:
-        # Determine next cell
-        match direction:
-            case "^":
-                next_x, next_y = x - 1, y
-            case "v":
-                next_x, next_y = x + 1, y
-            case "<":
-                next_x, next_y = x, y - 1
-            case ">":
-                next_x, next_y = x, y + 1
 
-        # Guard patrols out of bounds
-        if (
-            next_x < 0
-            or next_x >= len(map_info.map)
-            or next_y < 0
-            or next_y >= len(map_info.map[0])
-        ):
-            break
+def move_position(position: GuardPosition) -> GuardPosition:
+    return GuardPosition(
+        position.x + position.direction[0],
+        position.y + position.direction[1],
+        position.direction,
+    )
 
-        # Turn right if an obstacle is encountered
-        if map_info.map[next_x][next_y]:
-            direction = _rotation_map[direction]
 
-        # Otherwise, move to next cell
-        else:
-            x, y = next_x, next_y
-            if (x, y, direction) in visited:
+def rotate_position(position: GuardPosition) -> GuardPosition:
+    return GuardPosition(
+        position.x,
+        position.y,
+        (position.direction[1], -position.direction[0]),
+    )
+
+
+class TestGuardPosition(TestCase):
+    def test(self):
+        guard = GuardPosition(0, 0, (0, 1))
+        self.assertEqual(move_position(guard), GuardPosition(0, 1, (0, 1)))
+        self.assertEqual(rotate_position(guard), GuardPosition(0, 0, (1, 0)))
+
+
+class TraversalAnalysis(NamedTuple):
+    visited: set[GuardPosition]
+    stuck: bool
+
+
+def unique_locations(traversal_analysis: TraversalAnalysis) -> set[tuple[int, int]]:
+    return set((p.x, p.y) for p in traversal_analysis.visited)
+
+
+class TestTraversalAnalysis(TestCase):
+    def test(self):
+        analysis = TraversalAnalysis(
+            {GuardPosition(0, 0, (0, 1)), GuardPosition(2, 5, (1, 0))},
+            False,
+        )
+        self.assertEqual(
+            unique_locations(analysis),
+            {(0, 0), (2, 5)},
+        )
+
+
+class DaySixSolver(Solver):
+    puzzle_map: list[list[bool]]
+    guard_origin: GuardPosition
+
+    @override
+    def __init__(self, puzzle_input: str):
+        self.puzzle_map = []
+        guard_origin = None
+
+        for x, line in enumerate(puzzle_input.strip().split("\n")):
+            line_list = list()
+            for y, cell in enumerate(line):
+                if cell in direction_map:
+                    guard_origin = GuardPosition(x, y, direction_map[cell])
+                line_list.append(cell == "#")
+            self.puzzle_map.append(line_list)
+
+        if guard_origin is None:
+            raise ValueError("Guard not found in map")
+
+        self.guard_origin = guard_origin
+
+        if not all(len(line) == len(self.puzzle_map[0]) for line in self.puzzle_map):
+            raise ValueError("Map is not rectangular")
+
+    @override
+    def solve_p1(self) -> int:
+        traversal_analysis = self.traverse_map()
+        return len(unique_locations(traversal_analysis))
+
+    @override
+    def solve_p2(self) -> int:
+        candidate_locations = unique_locations(self.traverse_map())
+        candidate_locations.discard((self.guard_origin.x, self.guard_origin.y))
+        verified_locations = set()
+
+        for x, y in candidate_locations:
+            if not self.puzzle_map[x][y]:
+                self.puzzle_map[x][y] = True
+                if self.traverse_map().stuck:
+                    verified_locations.add((x, y))
+                self.puzzle_map[x][y] = False
+
+        return len(verified_locations)
+
+    def out_of_bounds(self, guard_position: GuardPosition) -> bool:
+        return (
+            guard_position.x < 0
+            or guard_position.x >= len(self.puzzle_map)
+            or guard_position.y < 0
+            or guard_position.y >= len(self.puzzle_map[0])
+        )
+
+    def traverse_map(self) -> TraversalAnalysis:
+        position = self.guard_origin
+        visited = set({position})
+
+        while True:
+            next_position = move_position(position)
+            if self.out_of_bounds(next_position):
+                return TraversalAnalysis(visited, False)
+
+            # Obstacle is encountered
+            if self.puzzle_map[next_position.x][next_position.y]:
+                next_position = rotate_position(position)
+
+            # Guard is stuck
+            if next_position in visited:
                 return TraversalAnalysis(visited, True)
-            visited.add((x, y, direction))
 
-    return TraversalAnalysis(visited, False)
+            position = next_position
+            visited.add(position)
+
+
+class TestDaySixSolver(TestCase):
+    def test(self):
+        solver = DaySixSolver(
+            dedent(
+                """
+                ....#.....
+                .........#
+                ..........
+                ..#.......
+                .......#..
+                ..........
+                .#..^.....
+                ........#.
+                #.........
+                ......#...
+                """
+            )
+        )
+        self.assertEqual(solver.guard_origin, GuardPosition(6, 4, (-1, 0)))
+        self.assertEqual(solver.solve_p1(), 41)
+        self.assertEqual(solver.solve_p2(), 6)
diff --git a/puzzles/7.py b/puzzles/7.py
index 9437c31..a499837 100644
--- a/puzzles/7.py
+++ b/puzzles/7.py
@@ -1,46 +1,10 @@
 from functools import partial
 from math import log
-from typing import Callable, Iterator, NamedTuple
+from textwrap import dedent
+from typing import Callable, Iterator, NamedTuple, override
+from unittest import TestCase
 
-test_input = """
-190: 10 19
-3267: 81 40 27
-83: 17 5
-156: 15 6
-7290: 6 8 6 15
-161011: 16 10 13
-192: 17 8 14
-21037: 9 7 18 13
-292: 11 6 16 20
-"""
-
-test_solution_p1 = 3749
-test_solution_p2 = 11387
-
-
-def solve_p1(puzzle_input: str) -> int:
-    equations = _parse_equations(puzzle_input)
-    calibration_guard = partial(
-        _is_calibrated,
-        [
-            int.__add__,
-            int.__mul__,
-        ],
-    )
-    return sum(equation.target for equation in filter(calibration_guard, equations))
-
-
-def solve_p2(puzzle_input: str) -> int:
-    equations = _parse_equations(puzzle_input)
-    calibration_guard = partial(
-        _is_calibrated,
-        [
-            int.__add__,
-            int.__mul__,
-            _concat_ints,
-        ],
-    )
-    return sum(equation.target for equation in filter(calibration_guard, equations))
+from puzzles._solver import Solver
 
 
 class Equation(NamedTuple):
@@ -48,36 +12,98 @@ class Equation(NamedTuple):
     factors: tuple[int, ...]
 
 
-def _parse_equations(puzzle_input: str) -> Iterator[Equation]:
-    for line in puzzle_input.strip().split("\n"):
-        if line:
-            result_string, _, factors_string = line.partition(": ")
-            yield Equation(
-                int(result_string),
-                tuple(map(int, factors_string.split(" "))),
-            )
-
-
 Operator = Callable[[int, int], int]
 
 
-def _is_calibrated(operators: list[Operator], equation: Equation) -> bool:
-    def _eval_permutations(factors: tuple[int, ...]) -> Iterator[int]:
+def is_calibrated(operators: list[Operator], equation: Equation) -> bool:
+    def eval_permutations(factors: tuple[int, ...]) -> Iterator[int]:
         assert len(factors) > 0
         tail = factors[-1]
         if len(factors) == 1:
             yield tail
             return
-        for head in _eval_permutations(factors[:-1]):
+        for head in eval_permutations(factors[:-1]):
             if head > equation.target:
                 continue
             for operator in operators:
                 yield operator(head, tail)
 
     return any(
-        result == equation.target for result in _eval_permutations(equation.factors)
+        result == equation.target for result in eval_permutations(equation.factors)
     )
 
 
-def _concat_ints(a: int, b: int) -> int:
+def concat_ints(a: int, b: int) -> int:
     return 10 ** int(log(b, 10) + 1) * a + b
+
+
+class TestEquation(TestCase):
+    def test_is_calibrated(self):
+        equation = Equation(190, (10, 19))
+        self.assertTrue(is_calibrated([int.__add__, int.__mul__], equation))
+        self.assertFalse(is_calibrated([int.__add__], equation))
+
+    def test_concat_ints(self):
+        self.assertEqual(concat_ints(1, 2), 12)
+        self.assertEqual(concat_ints(12, 345), 12345)
+
+
+class DaySevenSolver(Solver):
+    equations: list[Equation]
+
+    @override
+    def __init__(self, puzzle_input: str):
+        self.equations = []
+        for line in puzzle_input.strip().split("\n"):
+            result_string, _, factors_string = line.partition(": ")
+            self.equations.append(
+                Equation(
+                    int(result_string),
+                    tuple(map(int, factors_string.split(" "))),
+                )
+            )
+
+    @override
+    def solve_p1(self) -> int:
+        return sum(
+            equation.target
+            for equation in filter(
+                partial(is_calibrated, [int.__add__, int.__mul__]),
+                self.equations,
+            )
+        )
+
+    @override
+    def solve_p2(self) -> int:
+        return sum(
+            equation.target
+            for equation in filter(
+                partial(is_calibrated, [int.__add__, int.__mul__, concat_ints]),
+                self.equations,
+            )
+        )
+
+
+class TestDaySevenSolver(TestCase):
+    def test(self):
+        solver = DaySevenSolver(
+            dedent(
+                """
+                190: 10 19
+                3267: 81 40 27
+                83: 17 5
+                156: 15 6
+                7290: 6 8 6 15
+                161011: 16 10 13
+                192: 17 8 14
+                21037: 9 7 18 13
+                292: 11 6 16 20
+                """
+            )
+        )
+        self.assertEqual(
+            solver.equations[0],
+            Equation(190, (10, 19)),
+        )
+        self.assertEqual(solver.solve_p1(), 3749)
+        self.assertEqual(solver.solve_p2(), 11387)
diff --git a/puzzles/8.py b/puzzles/8.py
index 2e3ea81..5027ab3 100644
--- a/puzzles/8.py
+++ b/puzzles/8.py
@@ -1,110 +1,117 @@
+from functools import reduce
 from itertools import combinations
-from typing import NamedTuple
+from textwrap import dedent
+from typing import Set, override
+from unittest import TestCase
 
-test_input = """
-............
-........0...
-.....0......
-.......0....
-....0.......
-......A.....
-............
-............
-........A...
-.........A..
-............
-............
-"""
+from puzzles._solver import Solver
 
-test_solution_p1 = 14
-test_solution_p2 = 34
+Point = tuple[int, int]
 
 
-def solve_p1(puzzle_input: str) -> int:
-    grid = _parse_signal_grid(puzzle_input)
-    antinodes = _calculate_antinodes(grid)
-    # _print_grid(grid, antinodes)
-    return len(antinodes)
-
-
-def solve_p2(puzzle_input: str) -> int:
-    grid = _parse_signal_grid(puzzle_input)
-    antinodes = _calculate_antinodes(grid, harmonic=True)
-    # _print_grid(grid, antinodes)
-    return len(antinodes)
-
-
-class Point(NamedTuple):
-    x: int
-    y: int
-
-
-class SignalGrid(NamedTuple):
+class DayEightSolver(Solver):
     width: int
     height: int
     antenna_arrays: dict[str, set[Point]]
 
+    @override
+    def __init__(self, puzzle_input: str):
+        self.antenna_arrays = {}
 
-def _parse_signal_grid(puzzle_input: str) -> SignalGrid:
-    lines = puzzle_input.strip().split("\n")
-    antenna_arrays: dict[str, set[Point]] = {}
+        lines = puzzle_input.strip().split("\n")
+        self.width = len(lines[0])
+        self.height = len(lines)
 
-    for x, line in enumerate(lines):
-        for y, char in enumerate(line):
-            if char.isalnum():
-                if char not in antenna_arrays:
-                    antenna_arrays[char] = set()
-                antenna_arrays[char].add(Point(x, y))
+        for x, line in enumerate(puzzle_input.strip().split("\n")):
+            for y, char in enumerate(line):
+                if char.isalnum():
+                    if char not in self.antenna_arrays:
+                        self.antenna_arrays[char] = set()
+                    self.antenna_arrays[char].add((x, y))
 
-    return SignalGrid(len(lines[0]), len(lines), antenna_arrays)
+    @override
+    def solve_p1(self) -> int:
+        return len(
+            reduce(
+                Set.union,
+                (
+                    self.antinodes(a, b, harmonic=False)
+                    for antenna_array in self.antenna_arrays.values()
+                    for a, b in combinations(antenna_array, 2)
+                ),
+            )
+        )
+
+    @override
+    def solve_p2(self) -> int:
+        return len(
+            reduce(
+                Set.union,
+                (
+                    self.antinodes(a, b, harmonic=True)
+                    for antenna_array in self.antenna_arrays.values()
+                    for a, b in combinations(antenna_array, 2)
+                ),
+            )
+        )
+
+    def antinodes(self, a: Point, b: Point, harmonic=False) -> set[Point]:
+        points = set()
+
+        dx = b[0] - a[0]
+        dy = b[1] - a[1]
+
+        if harmonic:
+            antinode = a
+            while self.is_in_grid(antinode):
+                points.add(antinode)
+                antinode = (antinode[0] - dx, antinode[1] - dy)
+
+            antinode = b
+            while self.is_in_grid(antinode):
+                points.add(antinode)
+                antinode = (antinode[0] + dx, antinode[1] + dy)
+
+        else:
+            antinode = (a[0] - dx, a[1] - dy)
+            if self.is_in_grid(antinode):
+                points.add(antinode)
+
+            antinode = (b[0] + dx, b[1] + dy)
+            if self.is_in_grid(antinode):
+                points.add(antinode)
+
+        return points
+
+    def is_in_grid(self, point: Point) -> bool:
+        return 0 <= point[0] < self.height and 0 <= point[1] < self.width
 
 
-def _calculate_antinodes(grid: SignalGrid, harmonic=False) -> set[Point]:
-    antinodes: set[Point] = set()
-
-    for antenna_array in grid.antenna_arrays.values():
-        for a, b in combinations(antenna_array, 2):
-            dx = b.x - a.x
-            dy = b.y - a.y
-
-            # Left antinodes
-            if harmonic:
-                antinode = a
-                while True:
-                    antinodes.add(antinode)
-                    antinode = Point(antinode.x - dx, antinode.y - dy)
-                    if not _is_in_grid(grid, antinode):
-                        break
-            else:
-                antinode = Point(a.x - dx, a.y - dy)
-                if _is_in_grid(grid, antinode):
-                    antinodes.add(antinode)
-
-            # Right antinodes
-            if harmonic:
-                antinode = b
-                while True:
-                    antinodes.add(antinode)
-                    antinode = Point(antinode.x + dx, antinode.y + dy)
-                    if not _is_in_grid(grid, antinode):
-                        break
-            else:
-                antinode = Point(b.x + dx, b.y + dy)
-                if _is_in_grid(grid, antinode):
-                    antinodes.add(antinode)
-
-    return antinodes
-
-
-def _is_in_grid(grid: SignalGrid, point: Point) -> bool:
-    return 0 <= point.x < grid.height and 0 <= point.y < grid.width
-
-
-def _print_grid(grid: SignalGrid, antinodes: set[Point]):
-    output = [["."] * grid.width for _ in range(grid.height)]
-    for antinode in antinodes:
-        output[antinode.x][antinode.y] = "#"
-    for frequency, antenna_array in grid.antenna_arrays.items():
-        for antenna in antenna_array:
-            output[antenna.x][antenna.y] = frequency
-    print("\n".join("".join(row) for row in output))
+class TestDayEightSolver(TestCase):
+    def test(self):
+        solver = DayEightSolver(
+            dedent(
+                """
+                ............
+                ........0...
+                .....0......
+                .......0....
+                ....0.......
+                ......A.....
+                ............
+                ............
+                ........A...
+                .........A..
+                ............
+                ............
+                """
+            )
+        )
+        self.assertEqual(solver.width, 12)
+        self.assertEqual(solver.height, 12)
+        self.assertSetEqual(
+            solver.antenna_arrays["0"],
+            {(1, 8), (2, 5), (3, 7), (4, 4)},
+        )
+        self.assertEqual(solver.solve_p1(), 14)
+        self.assertEqual(solver.solve_p2(), 34)
diff --git a/puzzles/9.py b/puzzles/9.py
index eb84203..66b041e 100644
--- a/puzzles/9.py
+++ b/puzzles/9.py
@@ -1,26 +1,166 @@
-from itertools import islice, pairwise
-from typing import NamedTuple
+from itertools import count, pairwise
+import math
+from typing import Iterable, NamedTuple, override
+from unittest import TestCase
 
-from more_itertools import chunked, sliced
+from more_itertools import chunked, ilen
 
-test_input = """
-2333133121414131402
-"""
-
-test_solution_p1 = 1928
-test_solution_p2 = 2858
+from puzzles._solver import Solver
 
 
-def solve_p1(puzzle_input: str) -> int:
-    blocks = _parse_blocks(puzzle_input)
-    compacted_blocks = _compact_blocks(blocks)
-    return _hash_blocks(compacted_blocks)
+class LinkedList[T]:
+    __head: "LinkedListNode[T] | None"
+    __tail: "LinkedListNode[T] | None"
+
+    __slots__ = ("__head", "__tail")
+
+    @property
+    def head(self) -> "LinkedListNode[T] | None":
+        if not self.__head and self.__tail:
+            self.__head = self.__tail
+        while self.__head and self.__head.left:
+            self.__head = self.__head.left
+        return self.__head
+
+    @property
+    def tail(self) -> "LinkedListNode[T] | None":
+        if not self.__tail and self.__head:
+            self.__tail = self.__head
+        while self.__tail and self.__tail.right:
+            self.__tail = self.__tail.right
+        return self.__tail
+
+    def __init__(self, *values: Iterable[T]) -> None:
+        self.__head = None
+        self.__tail = None
+
+        for value in values:
+            self.append(value)
+
+    def append(self, value: T) -> None:
+        if tail := self.tail:
+            self.__tail = LinkedListNode(value, tail, None)
+            tail.right = self.__tail
+        else:
+            self.__tail = LinkedListNode(value, None, None)
+
+    def prepend(self, value: T) -> None:
+        if head := self.head:
+            self.__head = LinkedListNode(value, None, head)
+            head.left = self.__head
+        else:
+            self.__head = LinkedListNode(value, None, None)
+
+    def pop_tail(self) -> T | None:
+        if (tail := self.tail) is None:
+            raise IndexError("pop from empty LinkedList")
+
+        if tail.left:
+            tail.left.right = None
+
+        self.__tail = tail.left
+        tail.left = None
+
+        return tail.value
+
+    def pop_head(self) -> T:
+        if (head := self.head) is None:
+            raise IndexError("pop from empty LinkedList")
+
+        if head.right:
+            head.right.left = None
+
+        self.__head = head.right
+        head.right = None
+
+        return head.value
+
+    def copy(self) -> "LinkedList[T]":
+        return LinkedList(*self)
+
+    def __iter__(self) -> Iterable[T]:
+        node = self.head
+        while node is not None:
+            yield node.value
+            node = node.right
+
+    def __reversed__(self) -> Iterable[T]:
+        node = self.tail
+        while node is not None:
+            yield node.value
+            node = node.left
+
+    def __len__(self) -> int:
+        return ilen(self)
+
+    def __str__(self) -> str:
+        return f"LinkedList({', '.join(map(str, self))})"
 
 
-def solve_p2(puzzle_input: str) -> int:
-    blocks = _parse_blocks(puzzle_input)
-    compacted_blocks = _compact_blocks_no_fragmentation(blocks)
-    return _hash_blocks(compacted_blocks)
+class LinkedListNode[T]:
+    value: T
+    left: "LinkedListNode[T] | None"
+    right: "LinkedListNode[T] | None"
+
+    __slots__ = ("value", "left", "right")
+
+    def __init__(
+        self,
+        value: T,
+        left: "LinkedListNode[T] | None",
+        right: "LinkedListNode[T] | None",
+    ) -> None:
+        self.value = value
+        self.left = left
+        self.right = right
+
+    def insert_left(self, value: T) -> None:
+        node = LinkedListNode(value, self.left, self)
+        if self.left:
+            self.left.right = node
+        self.left = node
+
+    def insert_right(self, value: T) -> None:
+        node = LinkedListNode(value, self, self.right)
+        if self.right:
+            self.right.left = node
+        self.right = node
+
+    def pop(self) -> T:
+        if self.left:
+            self.left.right = self.right
+        if self.right:
+            self.right.left = self.left
+        return self.value
+
+
+class TestLinkedList(TestCase):
+    def test(self):
+        linked_list = LinkedList(1, 2, 3, 4, 5)
+        self.assertEqual(linked_list.head.value, 1)
+        self.assertEqual(linked_list.tail.value, 5)
+        self.assertListEqual(list(linked_list), [1, 2, 3, 4, 5])
+        self.assertListEqual(list(reversed(linked_list)), [5, 4, 3, 2, 1])
+        self.assertEqual(len(linked_list), 5)
+
+        self.assertEqual(linked_list.pop_tail(), 5)
+        self.assertEqual(linked_list.tail.value, 4)
+        self.assertEqual(linked_list.pop_head(), 1)
+        self.assertEqual(linked_list.head.value, 2)
+        linked_list.append(6)
+        self.assertEqual(linked_list.tail.value, 6)
+        linked_list.prepend(7)
+        self.assertEqual(linked_list.head.value, 7)
+        self.assertListEqual(list(linked_list), [7, 2, 3, 4, 6])
+
+        middle = linked_list.tail.left.left
+        self.assertEqual(middle.value, 3)
+        middle.insert_left(8)
+        self.assertListEqual(list(linked_list), [7, 2, 8, 3, 4, 6])
+        middle.insert_right(9)
+        self.assertListEqual(list(linked_list), [7, 2, 8, 3, 9, 4, 6])
+        self.assertEqual(middle.pop(), 3)
+        self.assertListEqual(list(linked_list), [7, 2, 8, 9, 4, 6])
 
 
 class Block(NamedTuple):
@@ -29,110 +169,133 @@ class Block(NamedTuple):
     size: int
 
 
-def _parse_blocks(puzzle_input: str) -> list[Block]:
-    blocks: list[Block] = []
-    cursor_position = 0
-    current_id = 0
+def compact_drive(drive: LinkedList[Block]) -> LinkedList[Block]:
+    if not len(drive):
+        return drive
 
-    snapshot = map(int, puzzle_input.strip())
-    for pair in chunked(snapshot, 2):
-        if data_size := pair[0]:
-            blocks.append(Block(current_id, cursor_position, data_size))
-            cursor_position += data_size
-            current_id += 1
-        if len(pair) == 2:
-            cursor_position += pair[1]
+    drive = drive.copy()
+    moving = drive.pop_tail()
+    cursor = drive.head
+    assert cursor is not None
 
-    return blocks
+    while cursor.right is not None:
+        a = cursor.value
+        b = cursor.right.value
+        free_space = b.position - a.position - a.size
 
+        if not free_space:
+            cursor = cursor.right
+            continue
 
-def _compact_blocks(blocks: list[Block]) -> list[Block]:
-    assert blocks
-    blocks = blocks.copy()
+        insertion = Block(
+            moving.id,
+            a.position + a.size,
+            min(free_space, moving.size),
+        )
 
-    compacted_blocks: list[Block] = []
-    current_position = 0
-    moving_block = blocks.pop()
+        cursor.insert_right(insertion)
+        cursor = cursor.right
 
-    while blocks:
-        next_block = blocks.pop(0)
-        free_space = next_block.position - current_position
-        while free_space:
-            assert moving_block.size > 0
-            allocation = min(free_space, moving_block.size)
-            compacted_blocks.append(
-                Block(
-                    moving_block.id,
-                    current_position,
-                    allocation,
-                )
+        if insertion.size < moving.size:
+            moving = Block(
+                moving.id,
+                moving.position,
+                moving.size - insertion.size,
             )
-            current_position += allocation
-            free_space -= allocation
-            if moving_block.size > allocation:
-                moving_block = Block(
-                    moving_block.id,
-                    moving_block.position + allocation,
-                    moving_block.size - allocation,
-                )
-            elif blocks:
-                moving_block = blocks.pop()
-            else:
-                break
+        else:
+            moving = drive.pop_tail()
 
-        compacted_blocks.append(next_block)
-        current_position += next_block.size
-
-    compacted_blocks.append(
+    cursor.insert_right(
         Block(
-            moving_block.id,
-            current_position,
-            moving_block.size,
+            moving.id,
+            cursor.value.position + cursor.value.size,
+            moving.size,
         )
     )
 
-    return compacted_blocks
+    return drive
 
 
-def _compact_blocks_no_fragmentation(blocks: list[Block]) -> list[Block]:
-    assert blocks
-    blocks = blocks.copy()
+def compact_drive_without_fragmentation(drive: LinkedList[Block]) -> LinkedList[Block]:
+    if not len(drive):
+        return drive
 
-    compacted_blocks: list[Block] = []
+    drive = drive.copy()
+    moving = drive.tail
 
-    while len(blocks) > 1:
-        moving_block = blocks[-1]
-        for (_, a), (i, b) in pairwise(enumerate(blocks)):
+    while moving:
+        cursor = drive.head
+
+        while cursor != moving:
+            a = cursor.value
+            b = cursor.right.value
             free_space = b.position - a.position - a.size
-            if free_space >= moving_block.size:
-                modified_block = Block(
-                    moving_block.id,
-                    a.position + a.size,
-                    moving_block.size,
+
+            if free_space >= moving.value.size:
+                moving.pop()
+                cursor.insert_right(
+                    Block(
+                        moving.value.id,
+                        a.position + a.size,
+                        moving.value.size,
+                    )
                 )
-                blocks.pop()
-                blocks.insert(i, modified_block)
                 break
-        else:
-            blocks.pop()
-            compacted_blocks.append(moving_block)
 
-    compacted_blocks.append(blocks[0])
+            cursor = cursor.right
 
-    return list(sorted(compacted_blocks, key=lambda block: block.position))
+        moving = moving.left
+
+    return drive
 
 
-def _print_blocks(blocks: list[Block]) -> str:
+def hash_drive(drive: LinkedList[Block]) -> int:
+    return sum(
+        block.id * block.size * (block.position * 2 + block.size - 1) // 2
+        for block in drive
+    )
+
+
+def print_drive(drive: LinkedList[Block]) -> None:
     snapshot = []
-    for a, b in pairwise(blocks):
+    for a, b in pairwise(drive):
         snapshot.append(str(a.id) * a.size)
         snapshot.append("." * (b.position - a.position - a.size))
-    snapshot.append(str(blocks[-1].id) * blocks[-1].size)
+    snapshot.append(str(drive.tail.value.id) * drive.tail.value.size)
+    print("".join(snapshot))
 
 
-def _hash_blocks(blocks: list[Block]) -> int:
-    return sum(
-        block.id * pos
-        for block in blocks
-        for pos in range(block.position, block.position + block.size)
-    )
+class DayNineSolver(Solver):
+    drive: LinkedList[Block]
+
+    @override
+    def __init__(self, puzzle_input: str):
+        self.drive = LinkedList()
+        snapshot = map(int, puzzle_input.strip())
+        cursor_position = 0
+        current_id = count()
+
+        for pair in chunked(snapshot, 2):
+            if data_size := pair[0]:
+                id = next(current_id)
+                self.drive.append(Block(id, cursor_position, data_size))
+                cursor_position += data_size
+            if len(pair) == 2:
+                cursor_position += pair[1]
+
+    @override
+    def solve_p1(self) -> int:
+        compacted_drive = compact_drive(self.drive)
+        return hash_drive(compacted_drive)
+
+    @override
+    def solve_p2(self) -> int:
+        compacted_drive = compact_drive_without_fragmentation(self.drive)
+        return hash_drive(compacted_drive)
+
+
+class TestDayNineSolver(TestCase):
+    def test(self):
+        solver = DayNineSolver("2333133121414131402\n")
+        self.assertEqual(solver.solve_p1(), 1928)
+        self.assertEqual(solver.solve_p2(), 2858)
diff --git a/puzzles/_solver.py b/puzzles/_solver.py
new file mode 100644
index 0000000..f977b77
--- /dev/null
+++ b/puzzles/_solver.py
@@ -0,0 +1,12 @@
+from abc import ABC, abstractmethod
+
+
+class Solver(ABC):
+    @abstractmethod
+    def __init__(self, puzzle_input: str): ...
+
+    @abstractmethod
+    def solve_p1(self) -> int: ...
+
+    @abstractmethod
+    def solve_p2(self) -> int: ...
diff --git a/solve.py b/solve.py
index b15d625..8410349 100644
--- a/solve.py
+++ b/solve.py
@@ -1,80 +1,60 @@
 import sys
 from importlib import import_module
+from inspect import getmembers, isclass
 from time import time
+from unittest import TextTestRunner, defaultTestLoader
 
-from advent.errors import InvalidSessionIDError, PuzzleNotFoundError
 from advent.functions import get_puzzle_input
 
-
-def usage():
-    print("Usage: python solve.py <day>")
+from puzzles._solver import Solver
 
 
 def main():
     if len(sys.argv) != 2:
-        usage()
-        sys.exit(1)
+        raise RuntimeError("Usage: python solve.py <day>")
 
     try:
         day = int(sys.argv[1])
     except ValueError:
-        print("Day must be an integer")
-        usage()
-        sys.exit(1)
+        raise RuntimeError("Day must be an integer")
 
+    print(f"Loading 2024, day {day} solver...")
     try:
-        print(f"Loading 2024, day {day} solver")
         mod = import_module(f"puzzles.{day}")
     except ModuleNotFoundError:
         print(f"Solver for day {day} not found")
         sys.exit(1)
 
-    try:
-        print("Testing part 1 solution...")
-        test_input_p1 = getattr(mod, "test_input_p1", getattr(mod, "test_input", None))
-        start = time()
-        assert mod.solve_p1(test_input_p1) == mod.test_solution_p1
-        print(f"Test passed in {time() - start:.3f} seconds")
+    solvers = getmembers(mod, lambda m: isclass(m) and issubclass(m, Solver))
+    if len(solvers) == 0:
+        raise RuntimeError("No solver found")
+    solver_class: type[Solver] = solvers[0][1]
 
-        print("Testing part 2 solution...")
-        test_input_p2 = getattr(mod, "test_input_p2", getattr(mod, "test_input", None))
-        start = time()
-        assert mod.solve_p2(test_input_p2) == mod.test_solution_p2
-        print(f"Test passed in {time() - start:.3f} seconds")
+    test_suite = defaultTestLoader.loadTestsFromModule(mod)
+    test_runner = TextTestRunner(verbosity=0)
+    test_result = test_runner.run(test_suite)
+    if not test_result.wasSuccessful():
+        raise RuntimeError("Tests failed")
 
-    except AssertionError:
-        print("Test failed")
-        sys.exit(1)
+    print("Fetching puzzle input...")
+    puzzle_input = get_puzzle_input(2024, int(day))
 
-    except Exception as exc:
-        print("Error:", exc)
-        sys.exit(1)
+    solver = solver_class(puzzle_input)
 
-    try:
-        print("Fetching puzzle input...")
-        puzzle_input = get_puzzle_input(2024, int(day))
-    except (PuzzleNotFoundError, InvalidSessionIDError) as exc:
-        print(exc)
-        sys.exit(1)
+    print("Solving part 1...")
+    start = time()
+    solution_p1 = solver.solve_p1()
+    print(f"Part 1 solution: {solution_p1} ({time() - start:.3f} seconds)")
 
-    try:
-        print("Solving part 1...")
-        start = time()
-        solution_p1 = mod.solve_p1(puzzle_input)
-        print(f"Part 1 solution: {solution_p1} ({time() - start:.3f} seconds)")
-
-        print("Solving part 2...")
-        solution_p2 = mod.solve_p2(puzzle_input)
-        print(f"Part 2 solution: {solution_p2} ({time() - start:.3f} seconds)")
-
-    except NotImplementedError:
-        print("Puzzle solver is incomplete. Exiting")
-        sys.exit(1)
-
-    except Exception as exc:
-        print("Error:", exc)
-        sys.exit(1)
+    print("Solving part 2...")
+    start = time()
+    solution_p2 = solver.solve_p2()
+    print(f"Part 2 solution: {solution_p2} ({time() - start:.3f} seconds)")
 
 
 if __name__ == "__main__":
-    main()
+    try:
+        main()
+    except Exception as exc:
+        print(exc)
+        sys.exit(1)