diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..99e9c3f
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,4 @@
+{
+	"editor.insertSpaces": false,
+	"editor.detectIndentation": false
+}
\ No newline at end of file
diff --git a/main.lua b/main.lua
index d465ab0..4c8f967 100644
--- a/main.lua
+++ b/main.lua
@@ -9,8 +9,6 @@ local YELLOW = 2
 -- Utils
 --
 
-local a = BLUE
-
 function idx_xy(idx, width)
 	return (idx - 1) % width + 1, (idx - 1) \ width + 1
 end
@@ -63,20 +61,47 @@ function count(tbl, p)
 	return c
 end
 
+function find(tbl, o)
+	local indices = {}
+	for k,v in ipairs(tbl) do
+		if v == o then add(indices, k) end
+	end
+	return indices
+end
+
+-- shallow copy
+function copy(tbl)
+	local copy = {}
+	for v in all(tbl) do add(copy, v) end
+	return copy
+end
+
+-- shallow equality
+function equal(tbl1, tbl2)
+	for k, _ in ipairs(tbl1) do
+		if tbl1[k] ~= tbl2[k] then return false end
+	end
+	return true
+end
+
 --
 -- Board
 --
 
 local Board = {}
 function Board.new()
-	local width = 6
+	local width = 10
 	local t = [[
-		0, 0, 0, 0, 1, 0,
-		2, 0, 0, 0, 1, 2,
-		0, 0, 2, 0, 0, 0,
-		0, 0, 0, 1, 1, 0,
-		0, 0, 0, 0, 0, 0,
-		0, 0, 2, 0, 0, 2
+		2,0,2,0,0,2,1,0,1,2,
+		0,0,0,0,0,0,0,0,0,1,
+		0,1,0,0,0,0,0,0,0,0,
+		0,2,0,0,0,0,0,1,0,2,
+		0,0,1,0,0,2,0,1,0,1,
+		0,0,0,0,1,1,0,0,0,0,
+		0,2,2,0,0,0,0,0,0,2,
+		0,0,0,0,2,0,0,0,0,0,
+		0,0,2,0,0,1,0,0,0,0,
+		0,2,0,0,2,0,2,0,0,0
 	]]
 	local tiles = split(t)
 
@@ -214,7 +239,7 @@ function Board.new()
 		end,
 
 		fillRow = function(self, y, color)
-			printh("Filling line " .. y .. " in " .. color == BLUE and "blue" or "yellow")
+			printh("Filling line " .. y .. " in " .. (color == BLUE and "blue" or "yellow"))
 			local idx = self:xy_idx(1, y)
 			for i = idx, (idx+width-1) do
 				if self:getTile(i) == 0 then
@@ -224,7 +249,7 @@ function Board.new()
 		end,
 
 		fillCol = function(self, x, color)
-			printh("Filling column " .. x .. " in " .. color == BLUE and "blue" or "yellow")
+			printh("Filling column " .. x .. " in " .. (color == BLUE and "blue" or "yellow"))
 			local idx = self:xy_idx(x, 1)
 			for i = idx, #tiles, width do
 				if self:getTile(i) == 0 then
@@ -234,13 +259,73 @@ function Board.new()
 		end,
 
 		noIdenticalLines = function(self)
+			-- columns
+			local cols = self:getCols()
+			for x,col in ipairs(cols) do
+				if count(col, 0) == 2 and count(col, BLUE) == count(col, YELLOW) then
+			    local y1, y2 = unpack(find(col, 0))
+					local ab = copy(col) ab[y1] = BLUE ab[y2] = YELLOW
+					local ba = copy(col) ba[y1] = YELLOW ba[y2] = BLUE
+					-- Check if a dupe exists
+					for x2,col in ipairs(cols) do
+						if equal(col, ab) then
+							printh("No-dupe at col " .. x .. " from col " .. x2)
+							printh("  " .. self:xy_idx(x,y1) .. " in yellow")
+							printh("  " .. self:xy_idx(x,y2) .. " in blue")
+							self:fill(self:xy_idx(x,y1), YELLOW)
+							self:fill(self:xy_idx(x,y2), BLUE)
+							goto continue
+						elseif equal(col, ba) then
+							printh("No-dupe at col " .. x .. " from col " .. x2)
+							printh("  " .. self:xy_idx(x,y1) .. " in blue")
+							printh("  " .. self:xy_idx(x,y2) .. " in yellow")
+							self:fill(self:xy_idx(x,y1), BLUE)
+							self:fill(self:xy_idx(x,y2), YELLOW)
+							goto continue
+						end
+					end
+				end
+				::continue::
+			end
+
+			-- rows
+			local rows = self:getRows()
+			for y,row in ipairs(rows) do
+				if count(row, 0) == 2 and count(row, BLUE) == count(row, YELLOW) then
+			    local x1, x2 = unpack(find(row, 0))
+					local ab = copy(row) ab[x1] = BLUE ab[x2] = YELLOW
+					local ba = copy(row) ba[x1] = YELLOW ba[x2] = BLUE
+					-- Check if a dupe exists
+					for y2,row in ipairs(rows) do
+						if equal(row, ab) then
+							printh("No-dupe at row " .. y .. " from row " .. y2)
+							printh("  " .. self:xy_idx(x1,y) .. " in yellow")
+							printh("  " .. self:xy_idx(x2,y) .. " in blue")
+							self:fill(self:xy_idx(x1,y), YELLOW)
+							self:fill(self:xy_idx(x2,y), BLUE)
+							goto continue
+						elseif equal(row, ba) then
+							printh("No-dupe at row " .. y .. " from row " .. y2)
+							printh("  " .. self:xy_idx(x1,y) .. " in blue")
+							printh("  " .. self:xy_idx(x2,y) .. " in yellow")
+							self:fill(self:xy_idx(x1,y), BLUE)
+							self:fill(self:xy_idx(x2,y), YELLOW)
+							goto continue
+						end
+					end
+				end
+				::continue::
+			end
 		end,
 
 		draw = function(self)
 			for k,v in ipairs(tiles) do
 				local x,y = self:idx_xy(k)
 				local color = v == BLUE and 12 or v == YELLOW and 10 or 1
-				rectfill((x-1)*10 + x*8 + 4, (y-1)*10 + y*8 + 4, 12, 12, color)
+				local w = 10
+				local p = 1
+				rectfill((x-1)*w + (x-1)*(p+1), (y-1)*w + (y-1)*(p+1), w, w, color)
+				print(k, (x-1)*w + (x-1)*(p+1), (y-1)*w + (y-1)*(p+1), 8)
 			end
 		end
 	}
@@ -260,7 +345,9 @@ end
 
 function _draw()
 	cls()
-	if time() % 1 == 0 then
+	if time() % .5 == 0 then
+		printh("==")
+		printh("==")
 		board:solve()
 	end
 	board:draw()