diff --git a/12023/16/16.lua b/12023/16/16.lua
index da03df7..69794e3 100644
--- a/12023/16/16.lua
+++ b/12023/16/16.lua
@@ -12,50 +12,48 @@ for line in io.lines() do
         local char = line:sub(c,c)
         if char:match("[^%.]") then
             map[r][c] = char
-            print(char, c,r)
         end
     end
     r = r + 1
 end
 local height = r-1
-print(width, height)
 
 function coord(x,y)
     return y*1000+x
 end
 
-function energize(x, y)
+function energize(e,x, y)
     local c = coord(x,y)
-    energized[c] = energized[c] and (energized[c]+1) or 1
+    e[c] = e[c] and (e[c]+1) or 1
 end
 
-function mark_energized(xo, yo, xf, yf)
+function mark_energized(e, xo, yo, xf, yf)
     if xo==xf then -- vertical
         yo, yf = math.min(yo,yf), math.max(yo,yf)
         yo = math.max(1,yo)
         yf = math.min(height, yf)
         for y=yo,yf do
-            energize(xo,y)
+            energize(e,xo,y)
         end
     elseif yo==yf then --horizontal
         xo, xf = math.min(xo, xf), math.max(xo, xf)
         xo = math.max(1,xo)
         xf = math.min(width, xf)
         for x=xo,xf do
-            energize(x,yo)
+            energize(e,x,yo)
         end
     end
 end
 
-function count_energized()
+function count_energized(e)
     local count = 0
-    for c,v in pairs(energized) do
+    for c,v in pairs(e) do
         count = count + 1
     end
     return count
 end
 
-function next_beams(xs,ys,dx,dy,char)
+function next_beams(xs,ys,dx,dy,char,conditions)
     if not char then return nil end
     local cond = table.concat(com(xs,ys,dx,dy),",")
     if conditions[cond] then return nil
@@ -93,15 +91,27 @@ function next_beams(xs,ys,dx,dy,char)
         end
     elseif char=="/" then --mirrors
         if dx~=0 then
-            table.insert(beams, com(xs, ys-dx, 0, -dx))
+            ny = ys - dx
+            if ny>=1 and ny<=height then
+                table.insert(beams, com(xs, ny, 0, -dx))
+            end
         elseif dy~=0 then
-            table.insert(beams, com(xs-dy, ys, -dy, 0))
+            nx = xs - dy
+            if nx>=1 and nx<=width then
+                table.insert(beams, com(nx, ys, -dy, 0))
+            end
         end
     elseif char=="\\" then
         if dx~=0 then
-            table.insert(beams, com(xs, ys+dx, 0, dx))
+            ny = ys+dx
+            if ny>=1 and ny<=height then
+                table.insert(beams, com(xs, ny, 0, dx))
+            end
         elseif dy~=0 then
-            table.insert(beams, com(xs+dy, ys, dy, 0))
+            nx = xs + dy
+            if nx>=1 and nx<=width then
+                table.insert(beams, com(nx, ys, dy, 0))
+            end
         end
     end
     return beams
@@ -110,64 +120,99 @@ end
 com = table.pack
 exp = table.unpack
 
-energized = {}
-local beams = {}
-conditions = {}
-table.insert(beams, com(1,1,1,0))
---table.insert(beams, com(3,9,-1,0))
 
-repeat
-    local beam = table.remove(beams)
-    local x,y,dx,dy = exp(beam)
-    print("\nbeam", x, y, dx, dy)
-    local xf, yf = 0,0
-    local charf = nil
-    --search next
-    if dx~= 0 then
-        local xm = x
-        local found = nil
-        repeat
-            if map[y][xm] then
-                found = map[y][xm]
-            else
-                xm = xm + dx
-            end
-        until found or xm<1 or xm>width
-        xf, yf = xm, y
-        charf = found
-    elseif dy~= 0 then
-        local ym = y
-        local found = nil
-        repeat
-            if map[ym][x] then
-                found = map[ym][x]
-            else
-                ym = ym + dy
-            end
-        until found or ym<1 or ym>height
-        xf,yf = x,ym
-        charf = found
-    end
-
-    print("found", charf, xf, yf)
-    -- mark energized
-    mark_energized(x,y,xf,yf)
-    local nb = next_beams(xf, yf, dx, dy, charf)
-    if nb then
-        for _, b in ipairs(nb) do
-            table.insert(beams, b)
+function activate(x, y, dx, dy)
+    local beams = {}
+    local energized = {}
+    local conditions = {}
+    table.insert(beams, com(x,y,dx,dy))
+    repeat
+        local beam = table.remove(beams)
+        local x,y,dx,dy = exp(beam)
+        --print("\nbeam", x, y, dx, dy)
+        local xf, yf = 0,0
+        local charf = nil
+        --search next
+        if dx~= 0 then
+            local xm = x
+            local found = nil
+            repeat
+                if map[y][xm] then
+                    found = map[y][xm]
+                else
+                    xm = xm + dx
+                end
+            until found or xm<1 or xm>width
+            xf, yf = xm, y
+            charf = found
+        elseif dy~= 0 then
+            local ym = y
+            local found = nil
+            repeat
+                if map[ym][x] then
+                    found = map[ym][x]
+                else
+                    ym = ym + dy
+                end
+            until found or ym<1 or ym>height
+            xf,yf = x,ym
+            charf = found
         end
-    end
-until #beams==0
 
+        --print("found", charf, xf, yf)
+        -- mark energized
+        mark_energized(energized,x,y,xf,yf)
+        local nb = next_beams(xf, yf, dx, dy, charf, conditions)
+        if nb then
+            for _, b in ipairs(nb) do
+                table.insert(beams, b)
+            end
+        end
+    until #beams==0
 
-for y=1,height do
-    local s = ""
-    for x=1,width do
-        local char = energized[coord(x,y)] and "#" or "."
-        s = s..char
+    --[[
+    for y=1,height do
+        local s = ""
+        for x=1,width do
+            local char = energized[coord(x,y)] and "#" or "."
+            s = s..char
+        end
+        print(s)
     end
-    print(s)
+    --]]
+    return count_energized(energized)
 end
 
-print("part 1", count_energized())
+
+print("part 1", activate(1,1,1,0))
+
+local max = 0
+local max_conds = com(0,0,0,0)
+
+-- from the top and bottom
+for x=1,width do
+    local r = activate(x,1,0,1)
+    if r>max then
+        max, max_conds = r, com(x,1,0,1)
+    end
+    r = activate(x,height,0,-1)
+    if r>max then
+        max, max_conds = r, com(x,height,0,-1)
+    end
+end
+
+-- from the left and right
+for y=1,height do
+    local r = activate(1,y,1,0)
+    if r>max then
+        max, max_conds = r, com(1,y,1,0)
+    end
+    r = activate(width,y,-1,0)
+    if r>max then
+        max, max_conds = r, com(width,y,-1,0)
+    end
+end
+
+
+print(table.concat(max_conds,","))
+print("part 2", max)