diff --git a/2015-python/solutions/day_13.py b/2015-python/solutions/day_13.py
new file mode 100644
index 0000000..a9c9acf
--- /dev/null
+++ b/2015-python/solutions/day_13.py
@@ -0,0 +1,50 @@
+from collections import defaultdict
+from itertools import permutations, pairwise
+from solutions import BaseSolution
+
+
+class Solution(BaseSolution):
+    input_file = "13.txt"
+
+    def __str__(self):
+        return "Day 13: Knights of the Dinner Table"
+
+    def parse_input(self, data):
+        lines = defaultdict(int)
+
+        def parseline(line):
+            a, _w, gain_or_lose, value, _h, _u, _b, _s, _n, _t, b = line.split()
+            units = -int(value) if gain_or_lose == "lose" else int(value)
+            return (f"{a}-{b[:-1]}", units)
+
+        for k, v in [parseline(line) for line in data.strip().splitlines()]:
+            lines[k] = v
+
+        return lines
+
+    def _solve(self, people, puzzle_input):
+        def happiness(seats):
+            neighbours = list(pairwise(seats))
+            neighbours.append((seats[0], seats[-1]))
+            return sum(
+                [
+                    sum(puzzle_input["-".join([a, b])] for a, b in neighbours),
+                    sum(puzzle_input["-".join([b, a])] for a, b in neighbours[::-1]),
+                ]
+            )
+
+        return max(happiness(seats) for seats in permutations(people, len(people)))
+
+    def solve(self, puzzle_input):
+        people = set([ab.split("-")[0] for ab, _v in puzzle_input.items()])
+        return self._solve(people, puzzle_input)
+
+    def solve_again(self, puzzle_input):
+        people = set([ab.split("-")[0] for ab, _v in puzzle_input.items()])
+        people.add("-")
+        return self._solve(people, puzzle_input)
+
+
+if __name__ == "__main__":
+    solution = Solution()
+    solution.show_results()
diff --git a/2015-python/tests/test_day_13.py b/2015-python/tests/test_day_13.py
new file mode 100644
index 0000000..0fc7096
--- /dev/null
+++ b/2015-python/tests/test_day_13.py
@@ -0,0 +1,46 @@
+import unittest
+
+from solutions.day_13 import Solution
+
+
+class Day13TestCase(unittest.TestCase):
+    def setUp(self):
+        self.solution = Solution()
+        self.puzzle_input = self.solution.parse_input(
+            """
+Alice would gain 54 happiness units by sitting next to Bob.
+Alice would lose 79 happiness units by sitting next to Carol.
+Alice would lose 2 happiness units by sitting next to David.
+Bob would gain 83 happiness units by sitting next to Alice.
+Bob would lose 7 happiness units by sitting next to Carol.
+Bob would lose 63 happiness units by sitting next to David.
+Carol would lose 62 happiness units by sitting next to Alice.
+Carol would gain 60 happiness units by sitting next to Bob.
+Carol would gain 55 happiness units by sitting next to David.
+David would gain 46 happiness units by sitting next to Alice.
+David would lose 7 happiness units by sitting next to Bob.
+David would gain 41 happiness units by sitting next to Carol.
+        """
+        )
+
+    def test_parse_puzzle_input(self):
+        data = """
+Alice would gain 54 happiness units by sitting next to Bob.
+Alice would lose 79 happiness units by sitting next to Carol.
+        """
+        assert self.solution.parse_input(data) == dict(
+            [
+                ("Alice-Bob", 54),
+                ("Alice-Carol", -79),
+            ]
+        )
+
+    def test_solve_first_part(self):
+        assert self.solution.solve(self.puzzle_input) == 330
+
+    # def test_solve_second_part(self):
+    #     assert self.solution.solve_again(self.puzzle_input) == True
+
+
+if __name__ == "__main__":
+    unittest.main()