--- a/15/15.jl	Sat Dec 17 12:33:38 2022 +0100
+++ b/15/15.jl	Sat Dec 17 13:11:15 2022 +0100
@@ -34,12 +34,12 @@
     v
 end
 
-function point_is_within_closest(p::Point, b::Beacon)::Bool
-    distance(p, b.sensor) <= b.dist && p != b.beacon
+function point_is_within_closest(p::Point, b::Beacon; ignorebeacon=false)::Bool
+    distance(p, b.sensor) <= b.dist && (ignorebeacon || p != b.beacon)
 end
 
-function point_is_covered(p::Point, bs::Vector{Beacon})::Bool
-    any(b -> point_is_within_closest(p, b), bs)
+function point_is_covered(p::Point, bs::Vector{Beacon}; ignorebeacon=false)::Bool
+    any(b -> point_is_within_closest(p, b; ignorebeacon=ignorebeacon), bs)
 end
 
 function n_covered_points(bs::Vector{Beacon}, y::Int)::Int
@@ -50,9 +50,24 @@
     count
 end
 
-println(" === PART 1 === ");
+function find_distress_beacon(bs::Vector{Beacon}, minc=0, maxc=20)::Vector{Point}
+    reachable = Set{Point}();
+    for b in bs
+        @show b
+        for x = b.sensor.x-b.dist:b.sensor.x+b.dist
+            for y = b.sensor.y-abs(b.dist-abs(x-b.sensor.x)):b.sensor.y+abs(b.dist-abs(x-b.sensor.x))
+                push!(reachable, Point(x,y));
+            end
+        end
+    end
+    possible = [Point(x, y) for x = minc:maxc for y = minc:maxc if !in(Point(x,y), reachable)];
+    possible
+end
+
 bs = parse_lines("15/input.txt");
 println(n_covered_points(bs, 2000000));
+#println(find_distress_beacon(bs, 0, 4000000));
 
 bs = parse_lines("15/test_input.txt");
 println(n_covered_points(bs, 10));
+println(find_distress_beacon(bs));