Advent of Code 2019 - Lua
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orbits = {}
for line in io.lines(arg[1]) do
a, b = line:match("(%w+)%)(%w+)")
if not orbits[a] then
orbits[a] = {}
end
table.insert(orbits[a], b)
end
print("Parsed...")
pos_you = nil
pos_san = nil
function getorbits(a, branches, depth)
local value = depth
if not orbits[a] then
return value
end
local b = branches
if #orbits[a] > 1 then
b = {table.unpack(branches)}
table.insert(b, {depth=depth, name=a})
end
for _, orbit in ipairs(orbits[a]) do
if orbit == "YOU" then
pos_you = {branches=branches, depth=depth}
end
if orbit == "SAN" then
pos_san = {branches=branches, depth=depth}
end
value = value + getorbits(orbit, b, depth + 1)
end
return value
end
print("Part 1:", getorbits("COM", {}, 0))
commbranch = 1
while true do
if pos_you.branches[commbranch] ~= pos_san.branches[commbranch] then
break
end
commbranch = commbranch + 1
end
branch = pos_you.branches[commbranch - 1]
distance = pos_you.depth + pos_san.depth - branch.depth * 2
print("Part 2:", distance)