1 files changed, 30 insertions, 16 deletions

diff --git a/day15/__init__.py b/day15/__init__.py
index b43cae1..c22f0c1 100644
--- a/day15/__init__.py
+++ b/day15/__init__.py
@@ -3,20 +3,21 @@ import re
 from abc import ABC
 from collections import namedtuple
 from dataclasses import dataclass, field
-from typing import Tuple, Iterator, Any, Set
+from typing import Tuple, Iterator, Any, Set, Union
 
 from aoc import BaseAssignment
 
 
 class Coordinate(namedtuple("Coordinate", ["x", "y"])):
     def distance(self, other: "Coordinate"):
-        return abs(other.x - self.x) + abs(other.y - self.y)
+        return abs(self.x - other.x) + abs(self.y - other.y)
 
 
 @dataclass
 class Sensor:
     coordinate: Coordinate
     nearest: Coordinate
+    radius: int = None
 
     def __hash__(self):
         return hash(self.coordinate)
@@ -24,6 +25,25 @@ class Sensor:
     def __post_init__(self):
         self.radius = self.coordinate.distance(self.nearest)
 
+    def within_radius(self, coordinate: Coordinate) -> bool:
+        distance = self.coordinate.distance(coordinate)
+        return distance <= self.radius
+
+    def x_coordinates_within_radius_at(self, y: int, map: "Map") -> Union[range, list]:
+
+        coordinate = Coordinate(self.coordinate.x, y)
+
+        if not self.within_radius(coordinate):
+            return []
+
+        dy = abs(self.coordinate.y - y)
+        left_over = self.radius - dy
+
+        return range(
+            max(self.coordinate.x - left_over, map.width[0]),
+            min(self.coordinate.x + left_over + 1, map.width[-1]),
+        )
+
 
 @dataclass
 class Map:
@@ -77,21 +97,15 @@ class AssignmentOne(Assignment):
     def run(self, input: Iterator[Tuple[Sensor, Coordinate]], y=2000000):
         map = self.create_map(input)
 
-        no_sensor = 0
-
-        for x in map.width:
-            coordinate = Coordinate(x, y)
-
-            for sensor in map.sensors:
-                if sensor.nearest == coordinate:
-                    break
-
-                distance = sensor.coordinate.distance(coordinate)
-                if distance <= sensor.radius:
-                    no_sensor += 1
-                    break
+        x_coordinates = {
+            x
+            for sensor in map.sensors
+            for x in sensor.x_coordinates_within_radius_at(y, map)
+        }
 
-        return no_sensor
+        return len(x_coordinates) - len(
+            [beacon.x for beacon in map.beacons if beacon.y == y]
+        )
 
 
 class AssignmentTwo(Assignment):