58 lines
1.1 KiB
Lua
Executable File
58 lines
1.1 KiB
Lua
Executable File
#!/usr/bin/env luajit
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local ZERO = string.byte("0", 1)
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local ONE = string.byte("1", 1)
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local lines = {}
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for line in io.lines(arg[3]) do
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local ones = {}
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for char = 1, #line do
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table.insert(ones, line:byte(char) == ONE)
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end
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table.insert(lines, ones)
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end
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function reduce(left, keep)
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local char = 1
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while #left > 1 and char <= #lines[1] do
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local ones = 0
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for k, line in pairs(left) do
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if lines[line][char] then
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ones = ones + 1
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end
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end
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local nleft = {}
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for k, line in pairs(left) do
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if keep(lines[line][char], ones, #left) then
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table.insert(nleft, line)
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end
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end
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left = nleft
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char = char + 1
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end
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return left[1]
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end
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function bin2dec(t)
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local v = 0
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for i = 1, #t do
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v = v * 2
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if t[i] then v = v + 1 end
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end
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return v
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end
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local indices = {}
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for line = 1, #lines do
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table.insert(indices, line)
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end
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local oxygen = reduce(indices, function (bit, ones, total)
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return (not bit or ones >= total/2) and (bit or ones < total/2)
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end)
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local co2 = reduce(indices, function (bit, ones, total)
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return (not bit or ones < total/2) and (bit or ones >= total/2)
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end)
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print(bin2dec(lines[oxygen]) * bin2dec(lines[co2]))
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