diff --git a/8-1.rb b/8-1.rb
new file mode 100755
index 0000000..e1ab33a
--- /dev/null
+++ b/8-1.rb
@@ -0,0 +1,80 @@
+#!/usr/bin/env ruby
+
+problem = 8
+input = File.readlines("#{problem}.input").map(&:strip)
+#input = DATA.read.split("\n")
+
+# Find diferent antennas
+signals = input.join.chars.uniq
+  .reject { _1 == "." }
+  .map { [_1, []] }
+  .to_h
+
+grid = input.map(&:chars)
+# map antenna locations
+signals.keys.each do |signal|
+  grid.each_with_index do |row, x|
+    row.each_with_index do |val, y|
+      signals[val] << [x, y] if val == signal
+    end
+  end
+end
+
+# calculate antinodes between all node pairs
+antinodes = []
+signals.each do |(signal, locations)|
+  locations.combination(2).each do |(first, second)|
+    x = (first.first - second.first).abs
+    y = (first.last - second.last).abs
+
+    if first.first < second.first
+      x1 = first.first - x
+      x2 = second.first + x
+    else
+      x1 = first.first + x
+      x2 = second.first - x
+    end
+
+    if first.last < second.last
+      y1 = first.last - y
+      y2 = second.last + y
+    else
+      y1 = first.last + y
+      y2 = second.last - y
+    end
+
+    antinode_1 = [x1, y1]
+    antinode_2 = [x2, y2]
+    #require "debug";debugger
+
+    antinodes << antinode_1 if x1 >= 0 && y1 >= 0 && x1 < grid.size && y1 < grid.first.size
+    antinodes << antinode_2 if x2 >= 0 && y2 >= 0 && x2 < grid.size && y2 < grid.first.size
+  end
+end
+
+p antinodes.uniq.size
+
+grid.each_with_index do |row, x|
+  row.each_with_index do |val, y|
+    if antinodes.index([x,y])
+      print "#"
+    else
+      print grid[x][y]
+    end
+  end
+  puts
+end
+
+__END__
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............
diff --git a/8-2.rb b/8-2.rb
new file mode 100755
index 0000000..dedf120
--- /dev/null
+++ b/8-2.rb
@@ -0,0 +1,92 @@
+#!/usr/bin/env ruby
+
+problem = 8
+input = File.readlines("#{problem}.input").map(&:strip)
+#input = DATA.read.split("\n")
+
+# Find diferent antennas
+signals = input.join.chars.uniq
+  .reject { _1 == "." }
+  .map { [_1, []] }
+  .to_h
+
+grid = input.map(&:chars)
+# map antenna locations
+signals.keys.each do |signal|
+  grid.each_with_index do |row, x|
+    row.each_with_index do |val, y|
+      signals[val] << [x, y] if val == signal
+    end
+  end
+end
+
+# calculate antinodes between all node pairs
+antinodes = []
+signals.each do |(signal, locations)|
+  locations.each { antinodes << _1 }
+  locations.combination(2).each do |(first, second)|
+    x = (first.first - second.first).abs
+    y = (first.last - second.last).abs
+
+    node1, node2 = first, second
+    loop do
+      if first.first < second.first
+        x1 = node1.first - x
+      else
+        x1 = node1.first + x
+      end
+      if first.last < second.last
+        y1 = node1.last - y
+      else
+        y1 = node1.last + y
+      end
+      node1 = [x1, y1]
+      break unless x1 >= 0 && y1 >= 0 && x1 < grid.size && y1 < grid.first.size
+      antinodes << node1
+    end
+
+    loop do
+      if first.first < second.first
+        x2 = node2.first + x
+      else
+        x2 = node2.first - x
+      end
+      if first.last < second.last
+        y2 = node2.last + y
+      else
+        y2 = node2.last - y
+      end
+
+      node2 = [x2, y2]
+      break unless x2 >= 0 && y2 >= 0 && x2 < grid.size && y2 < grid.first.size
+      antinodes << node2
+    end
+  end
+end
+
+p antinodes.uniq.size
+
+grid.each_with_index do |row, x|
+  row.each_with_index do |val, y|
+    if antinodes.index([x,y])
+      print "#"
+    else
+      print grid[x][y]
+    end
+  end
+  puts
+end
+
+__END__
+............
+........0...
+.....0......
+.......0....
+....0.......
+......A.....
+............
+............
+........A...
+.........A..
+............
+............
diff --git a/8.input b/8.input
new file mode 100644
index 0000000..697f756
--- /dev/null
+++ b/8.input
@@ -0,0 +1,50 @@
+.......................O......T.....d......M......
+..............................F...................
+..........V..................R....................
+............B..t..........T..........d............
+.....................B.........T................M.
+..V.................................2.......M.....
+.......V........................F.O..........2....
+...................................T..............
+..................................................
+......r..........B......................c.........
+.....o3.B.............................2...........
+..................1...m..o....d..c.....M..........
+......Qr....o............F....0............1......
+....Q.......................0....................2
+......t..........0................................
+.............R.................................mL.
+....r..............3.....................c..1.....
+.........Q.........................1..............
+................x...R.............................
+...x........8.R...................................
+..................8...............................
+........x.u.................Z.....................
+...........................X...............d......
+....................30.....................f......
+......q...............v...................c.......
+..........t8.........D.3..........................
+.......t.......4.............8....................
+...b..................C...........D...............
+.........................v..ND4..........K........
+.......F.........u...........C..............fZ....
+........X..9...........N.........Z..........k.....
+.............X.6...q..........................k...
+..............................C.Z...........m....k
+...................4.v..............N.............
+....................u.......D..............m......
+............................vl.....UK.............
+............................l..6.......f..........
+..................q.4............N................
+..........b....x..............fu..................
+.9..................................U.......l.....
+....w......b.........L......6.....z.5.............
+..........X..........W6........5............z.....
+...........q..........L............z........n...W.
+............................5.........n...W..z....
+........9........w................7....n..........
+............w......................7...K.....n....
+.........................U....K......W............
+.........w.....L.................k....7...........
+...................7.............l.............5..
+..............9...................................