37 lines
832 B
Lua
37 lines
832 B
Lua
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#!/usr/bin/env luajit
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require("utils")
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require("set")
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local graph = {}
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local lower = set()
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for line in io.lines(arg[3]) do
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local a, b = unpack(split(line, "-"))
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local as, bs = graph[a] or {}, graph[b] or {}
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table.insert(as, b)
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table.insert(bs, a)
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if string.lower(a) == a then lower:add(a) end
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if string.lower(b) == b then lower:add(b) end
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graph[a] = as
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graph[b] = bs
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end
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local function backtrack(i, once, smalls)
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if i == "end" then
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return 1
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else
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local paths = 0
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for k, v in pairs(graph[i]) do
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if not lower:has(v) or not once:has(v) then
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once:add(v)
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paths = paths + backtrack(v, once, smalls)
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once:remove(v)
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elseif smalls > 0 and v ~= "start" and v ~= "end" then
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paths = paths + backtrack(v, once, smalls - 1)
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end
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end
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return paths
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end
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end
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print(backtrack("start", set({"start"}), 1))
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