diff --git a/README.md b/README.md
index c25b697..bb7132e 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,7 @@ I use python 3.11 without any libraries beyond the standard.
 
 | Day | Time      | Rank  | Score | Time     | Rank  | Score |
 | --- | --------- | ----- | ----- | -------- | ----- | ----- |
+| 15  | 00:58:10  | 3963  |     0 | 02:26:22 |  4011 |     0 |
 | 14  | 00:58:39  |  4431 |     0 | 01:18:15 |  4620 |     0 |
 | 13  | 01:23:44  |  5522 |     0 | 01:45:59 |  5610 |     0 |
 | 12  | 01:43:14  |  6571 |     0 | 01:51:15 |  6246 |     0 |
diff --git a/advent/days/day15/__init__.py b/advent/days/day15/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/advent/days/day15/data/input.txt b/advent/days/day15/data/input.txt
new file mode 100644
index 0000000..3ee5618
--- /dev/null
+++ b/advent/days/day15/data/input.txt
@@ -0,0 +1,32 @@
+2000000/4000000
+Sensor at x=3859432, y=2304903: closest beacon is at x=3677247, y=3140958
+Sensor at x=2488890, y=2695345: closest beacon is at x=1934788, y=2667279
+Sensor at x=3901948, y=701878: closest beacon is at x=4095477, y=368031
+Sensor at x=2422190, y=1775708: closest beacon is at x=1765036, y=2000000
+Sensor at x=2703846, y=3282799: closest beacon is at x=2121069, y=3230302
+Sensor at x=172003, y=2579074: closest beacon is at x=-77667, y=3197309
+Sensor at x=1813149, y=1311283: closest beacon is at x=1765036, y=2000000
+Sensor at x=1704453, y=2468117: closest beacon is at x=1934788, y=2667279
+Sensor at x=1927725, y=2976002: closest beacon is at x=1934788, y=2667279
+Sensor at x=3176646, y=1254463: closest beacon is at x=2946873, y=2167634
+Sensor at x=2149510, y=3722117: closest beacon is at x=2121069, y=3230302
+Sensor at x=3804434, y=251015: closest beacon is at x=4095477, y=368031
+Sensor at x=2613561, y=3932220: closest beacon is at x=2121069, y=3230302
+Sensor at x=3997794, y=3291220: closest beacon is at x=3677247, y=3140958
+Sensor at x=98328, y=3675176: closest beacon is at x=-77667, y=3197309
+Sensor at x=2006541, y=2259601: closest beacon is at x=1934788, y=2667279
+Sensor at x=663904, y=122919: closest beacon is at x=1618552, y=-433244
+Sensor at x=1116472, y=3349728: closest beacon is at x=2121069, y=3230302
+Sensor at x=2810797, y=2300748: closest beacon is at x=2946873, y=2167634
+Sensor at x=1760767, y=2024355: closest beacon is at x=1765036, y=2000000
+Sensor at x=3098487, y=2529092: closest beacon is at x=2946873, y=2167634
+Sensor at x=1716839, y=634872: closest beacon is at x=1618552, y=-433244
+Sensor at x=9323, y=979154: closest beacon is at x=-245599, y=778791
+Sensor at x=1737623, y=2032367: closest beacon is at x=1765036, y=2000000
+Sensor at x=26695, y=3049071: closest beacon is at x=-77667, y=3197309
+Sensor at x=3691492, y=3766350: closest beacon is at x=3677247, y=3140958
+Sensor at x=730556, y=1657010: closest beacon is at x=1765036, y=2000000
+Sensor at x=506169, y=3958647: closest beacon is at x=-77667, y=3197309
+Sensor at x=2728744, y=23398: closest beacon is at x=1618552, y=-433244
+Sensor at x=3215227, y=3077078: closest beacon is at x=3677247, y=3140958
+Sensor at x=2209379, y=3030851: closest beacon is at x=2121069, y=3230302
diff --git a/advent/days/day15/data/test01.txt b/advent/days/day15/data/test01.txt
new file mode 100644
index 0000000..19d5711
--- /dev/null
+++ b/advent/days/day15/data/test01.txt
@@ -0,0 +1,15 @@
+10/20
+Sensor at x=2, y=18: closest beacon is at x=-2, y=15
+Sensor at x=9, y=16: closest beacon is at x=10, y=16
+Sensor at x=13, y=2: closest beacon is at x=15, y=3
+Sensor at x=12, y=14: closest beacon is at x=10, y=16
+Sensor at x=10, y=20: closest beacon is at x=10, y=16
+Sensor at x=14, y=17: closest beacon is at x=10, y=16
+Sensor at x=8, y=7: closest beacon is at x=2, y=10
+Sensor at x=2, y=0: closest beacon is at x=2, y=10
+Sensor at x=0, y=11: closest beacon is at x=2, y=10
+Sensor at x=20, y=14: closest beacon is at x=25, y=17
+Sensor at x=17, y=20: closest beacon is at x=21, y=22
+Sensor at x=16, y=7: closest beacon is at x=15, y=3
+Sensor at x=14, y=3: closest beacon is at x=15, y=3
+Sensor at x=20, y=1: closest beacon is at x=15, y=3
\ No newline at end of file
diff --git a/advent/days/day15/solution.py b/advent/days/day15/solution.py
new file mode 100644
index 0000000..3e2fb8d
--- /dev/null
+++ b/advent/days/day15/solution.py
@@ -0,0 +1,117 @@
+from __future__ import annotations
+from dataclasses import dataclass
+
+from typing import Iterator, Self
+
+day_num = 15
+
+
+def part1(lines: Iterator[str]) -> int:
+    row, _ = next(lines).split('/')
+    sensor_map = SensorMap.parse(lines)
+    return sensor_map.count_impossible(int(row))
+
+
+def part2(lines: Iterator[str]) -> int:
+    _, max_range = next(lines).split('/')
+    sensor_map = SensorMap.parse(lines)
+    return sensor_map.get_possible_frequency(int(max_range))
+
+
+Position = tuple[int, int]
+ColRange = tuple[int, int]
+
+
+@dataclass(slots=True, frozen=True)
+class Sensor:
+    sensor: Position
+    distance: int
+
+    @classmethod
+    def parse(cls, line: str) -> tuple[Self, Position]:
+        parts = line.split('=')
+        sensor = int(parts[1].split(',')[0].strip()), int(parts[2].split(':')[0].strip())
+        beacon = int(parts[3].split(',')[0].strip()), int(parts[4].strip())
+        return cls(sensor, Sensor.manhatten(sensor, beacon)), beacon
+
+    @classmethod
+    def manhatten(cls, first: Position, other: Position) -> int:
+        return abs(first[0] - other[0]) + abs(first[1] - other[1])
+
+    def col_range_at_row(self, row: int) -> ColRange | None:
+        col_distance = self.distance - abs(self.sensor[1] - row)
+        if col_distance < 0:
+            return None
+
+        from_x = self.sensor[0] - col_distance
+        to_x = self.sensor[0] + col_distance
+
+        return from_x, to_x
+
+
+@dataclass(slots=True, frozen=True)
+class SensorMap:
+    sensors: list[Sensor]
+    beacons: set[Position]
+
+    @classmethod
+    def parse(cls, lines: Iterator[str]) -> SensorMap:
+        sensors: list[Sensor] = []
+        beacons: set[Position] = set()
+        for line in lines:
+            sensor, beacon = Sensor.parse(line)
+            sensors.append(sensor)
+            beacons.add(beacon)
+        return cls(sensors, beacons)
+
+    def get_impossible(self, row: int) -> list[ColRange]:
+        col_ranges: list[ColRange] = []
+
+        for sensor in self.sensors:
+            x_range = sensor.col_range_at_row(row)
+            if x_range is None:
+                continue
+            from_x, to_x = x_range
+            col_ranges.append((from_x, to_x))
+
+        return col_ranges
+
+    @classmethod
+    def merged_col_ranges(cls, col_ranges: list[ColRange]) -> Iterator[ColRange]:
+        col_ranges = sorted(col_ranges)
+        current = col_ranges[0]
+        for col_range in col_ranges:
+            if current[1] < col_range[1]:
+                if current[1] < col_range[0]:
+                    yield current
+                    current = col_range
+                else:
+                    current = current[0], col_range[1]
+        yield current
+
+    def count_impossible(self, row: int) -> int:
+        col_ranges = self.get_impossible(row)
+
+        seen = sum(rng[1] - rng[0] + 1 for rng in SensorMap.merged_col_ranges(col_ranges))
+        beacons = len({beacon[0] for beacon in self.beacons if beacon[1] == row})
+
+        return seen - beacons
+
+    def get_possible(self, max_range: int) -> Position:
+        for row in range(max_range):
+            col_ranges = sorted(self.get_impossible(row))
+
+            curr1 = col_ranges[0][1]
+            for one0, one1 in col_ranges:
+                if curr1 < one1:
+                    if curr1 < one0:
+                        return curr1 + 1, row
+                    if one1 > max_range:
+                        break
+                    curr1 = one1
+
+        raise Exception("No best spot found")
+
+    def get_possible_frequency(self, max_range: int) -> int:
+        freq_x, freq_y = self.get_possible(max_range)
+        return freq_x * 4_000_000 + freq_y
diff --git a/advent/days/day15/test_solution.py b/advent/days/day15/test_solution.py
new file mode 100644
index 0000000..48ef866
--- /dev/null
+++ b/advent/days/day15/test_solution.py
@@ -0,0 +1,49 @@
+from advent.common import input
+
+from .solution import Sensor, SensorMap, day_num, part1, part2
+
+
+def test_part1():
+    lines = input.read_lines(day_num, 'test01.txt')
+    expected = 26
+    result = part1(lines)
+    assert result == expected
+
+
+def test_part2():
+    lines = input.read_lines(day_num, 'test01.txt')
+    expected = 56000011
+    result = part2(lines)
+    assert result == expected
+
+
+def test_parse():
+    input = "Sensor at x=2, y=18: closest beacon is at x=-2, y=15"
+    expected = Sensor((2, 18), 7), (-2, 15)
+    result = Sensor.parse(input)
+    assert result == expected
+
+
+def test_x_range():
+    input = "Sensor at x=8, y=7: closest beacon is at x=2, y=10"
+    sensor, _ = Sensor.parse(input)
+    assert sensor.col_range_at_row(10) == (2, 14)
+    assert sensor.col_range_at_row(11) == (3, 13)
+
+
+def test_impossible():
+    lines = input.read_lines(day_num, 'test01.txt')
+    next(lines)
+    sensor_map = SensorMap.parse(lines)
+    expected = 26
+    result = sensor_map.count_impossible(10)
+    assert result == expected
+
+
+def test_possible():
+    lines = input.read_lines(day_num, 'test01.txt')
+    next(lines)
+    sensor_map = SensorMap.parse(lines)
+    expected = 56000011
+    result = sensor_map.get_possible_frequency(20)
+    assert result == expected