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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)
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