1 files changed, 68 insertions, 0 deletions
diff --git a/08/2.lua b/08/2.lua
new file mode 100644
index 0000000..691123c
--- /dev/null
+++ b/08/2.lua
@@ -0,0 +1,68 @@
+require "ext"
+local heights = {}
+
+for line in io.lines() do
+	local trees = {}
+	line:gsub("%d",function(t)
+		local tree = {
+			height=tonumber(t),
+			scene = {up=0,down=0,left=0,right=0}
+		}
+		table.insert(trees,tree) 
+	end)
+	table.insert(heights,trees)
+end
+print("heights:",heights)
+local nrow,ncol = #heights, #heights[1]
+local maxscene = 0
+local function is_visible(row,col)
+	print("examining tree at ",row,col,heights[row][col].height)
+	local this_tree = heights[row][col]
+	--up
+	for i = row-1,1,-1 do
+		if this_tree.height > heights[i][col].height then
+			this_tree.scene.up = this_tree.scene.up + 1
+		else
+			this_tree.scene.up = this_tree.scene.up + 1
+			break
+		end
+	end
+	--down
+	for i = row+1,nrow do
+		if this_tree.height > heights[i][col].height then
+			this_tree.scene.down = this_tree.scene.down + 1
+		else
+			this_tree.scene.down = this_tree.scene.down + 1
+			break
+		end
+	end
+	--left
+	for i = col-1,1,-1 do
+		if this_tree.height > heights[row][i].height then
+			this_tree.scene.left = this_tree.scene.left + 1
+		else
+			this_tree.scene.left = this_tree.scene.left + 1
+			break
+		end
+	end
+	--right
+	for i = col+1,ncol do
+		if this_tree.height > heights[row][i].height then
+			this_tree.scene.right = this_tree.scene.right + 1
+		else
+			this_tree.scene.right = this_tree.scene.right + 1
+			break
+		end
+	end
+	local s = this_tree.scene
+	this_tree.scenescore = s.up * s.down * s.left * s.right
+	if this_tree.scenescore > maxscene then
+		maxscene = this_tree.scenescore
+	end
+end
+for row = 2, nrow-1 do
+	for col = 2, ncol-1 do
+		is_visible(row,col)
+	end
+end
+print(maxscene)