day 16, part 2!
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1ef198fd5e
commit
20578ca8de
181
12023/16/16.lua
181
12023/16/16.lua
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@ -12,50 +12,48 @@ for line in io.lines() do
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local char = line:sub(c,c)
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if char:match("[^%.]") then
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map[r][c] = char
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print(char, c,r)
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end
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end
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r = r + 1
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end
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local height = r-1
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print(width, height)
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function coord(x,y)
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return y*1000+x
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end
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function energize(x, y)
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function energize(e,x, y)
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local c = coord(x,y)
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energized[c] = energized[c] and (energized[c]+1) or 1
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e[c] = e[c] and (e[c]+1) or 1
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end
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function mark_energized(xo, yo, xf, yf)
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function mark_energized(e, xo, yo, xf, yf)
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if xo==xf then -- vertical
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yo, yf = math.min(yo,yf), math.max(yo,yf)
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yo = math.max(1,yo)
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yf = math.min(height, yf)
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for y=yo,yf do
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energize(xo,y)
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energize(e,xo,y)
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end
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elseif yo==yf then --horizontal
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xo, xf = math.min(xo, xf), math.max(xo, xf)
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xo = math.max(1,xo)
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xf = math.min(width, xf)
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for x=xo,xf do
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energize(x,yo)
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energize(e,x,yo)
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end
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end
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end
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function count_energized()
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function count_energized(e)
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local count = 0
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for c,v in pairs(energized) do
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for c,v in pairs(e) do
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count = count + 1
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end
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return count
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end
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function next_beams(xs,ys,dx,dy,char)
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function next_beams(xs,ys,dx,dy,char,conditions)
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if not char then return nil end
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local cond = table.concat(com(xs,ys,dx,dy),",")
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if conditions[cond] then return nil
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@ -93,15 +91,27 @@ function next_beams(xs,ys,dx,dy,char)
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end
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elseif char=="/" then --mirrors
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if dx~=0 then
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table.insert(beams, com(xs, ys-dx, 0, -dx))
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ny = ys - dx
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if ny>=1 and ny<=height then
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table.insert(beams, com(xs, ny, 0, -dx))
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end
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elseif dy~=0 then
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table.insert(beams, com(xs-dy, ys, -dy, 0))
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nx = xs - dy
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if nx>=1 and nx<=width then
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table.insert(beams, com(nx, ys, -dy, 0))
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end
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end
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elseif char=="\\" then
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if dx~=0 then
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table.insert(beams, com(xs, ys+dx, 0, dx))
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ny = ys+dx
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if ny>=1 and ny<=height then
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table.insert(beams, com(xs, ny, 0, dx))
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end
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elseif dy~=0 then
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table.insert(beams, com(xs+dy, ys, dy, 0))
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nx = xs + dy
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if nx>=1 and nx<=width then
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table.insert(beams, com(nx, ys, dy, 0))
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end
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end
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end
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return beams
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@ -110,64 +120,99 @@ end
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com = table.pack
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exp = table.unpack
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energized = {}
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local beams = {}
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conditions = {}
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table.insert(beams, com(1,1,1,0))
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--table.insert(beams, com(3,9,-1,0))
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repeat
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local beam = table.remove(beams)
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local x,y,dx,dy = exp(beam)
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print("\nbeam", x, y, dx, dy)
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local xf, yf = 0,0
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local charf = nil
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--search next
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if dx~= 0 then
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local xm = x
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local found = nil
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repeat
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if map[y][xm] then
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found = map[y][xm]
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else
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xm = xm + dx
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end
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until found or xm<1 or xm>width
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xf, yf = xm, y
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charf = found
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elseif dy~= 0 then
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local ym = y
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local found = nil
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repeat
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if map[ym][x] then
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found = map[ym][x]
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else
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ym = ym + dy
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end
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until found or ym<1 or ym>height
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xf,yf = x,ym
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charf = found
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end
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print("found", charf, xf, yf)
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-- mark energized
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mark_energized(x,y,xf,yf)
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local nb = next_beams(xf, yf, dx, dy, charf)
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if nb then
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for _, b in ipairs(nb) do
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table.insert(beams, b)
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function activate(x, y, dx, dy)
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local beams = {}
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local energized = {}
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local conditions = {}
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table.insert(beams, com(x,y,dx,dy))
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repeat
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local beam = table.remove(beams)
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local x,y,dx,dy = exp(beam)
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--print("\nbeam", x, y, dx, dy)
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local xf, yf = 0,0
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local charf = nil
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--search next
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if dx~= 0 then
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local xm = x
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local found = nil
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repeat
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if map[y][xm] then
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found = map[y][xm]
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else
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xm = xm + dx
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end
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until found or xm<1 or xm>width
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xf, yf = xm, y
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charf = found
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elseif dy~= 0 then
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local ym = y
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local found = nil
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repeat
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if map[ym][x] then
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found = map[ym][x]
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else
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ym = ym + dy
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end
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until found or ym<1 or ym>height
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xf,yf = x,ym
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charf = found
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end
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end
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until #beams==0
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--print("found", charf, xf, yf)
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-- mark energized
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mark_energized(energized,x,y,xf,yf)
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local nb = next_beams(xf, yf, dx, dy, charf, conditions)
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if nb then
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for _, b in ipairs(nb) do
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table.insert(beams, b)
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end
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end
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until #beams==0
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for y=1,height do
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local s = ""
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for x=1,width do
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local char = energized[coord(x,y)] and "#" or "."
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s = s..char
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--[[
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for y=1,height do
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local s = ""
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for x=1,width do
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local char = energized[coord(x,y)] and "#" or "."
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s = s..char
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end
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print(s)
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end
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print(s)
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--]]
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return count_energized(energized)
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end
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print("part 1", count_energized())
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print("part 1", activate(1,1,1,0))
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local max = 0
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local max_conds = com(0,0,0,0)
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-- from the top and bottom
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for x=1,width do
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local r = activate(x,1,0,1)
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if r>max then
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max, max_conds = r, com(x,1,0,1)
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end
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r = activate(x,height,0,-1)
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if r>max then
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max, max_conds = r, com(x,height,0,-1)
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end
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end
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-- from the left and right
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for y=1,height do
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local r = activate(1,y,1,0)
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if r>max then
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max, max_conds = r, com(1,y,1,0)
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end
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r = activate(width,y,-1,0)
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if r>max then
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max, max_conds = r, com(width,y,-1,0)
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end
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end
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print(table.concat(max_conds,","))
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print("part 2", max)
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