27 lines
661 B
D
27 lines
661 B
D
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import std;
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void main()
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{
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File("input", "r").byLine.findMissingSeatID.writeln;
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}
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auto calculateSeatID(const char[] seat)
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{
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return seat.retro.enumerate.map!(it => "BR".canFind(it.value) ? 2 ^^ it.index : 0).sum;
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}
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unittest
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{
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assert("FBFBBFFRLR".calculateSeatID == 357);
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assert("BFFFBBFRRR".calculateSeatID == 567);
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assert("FFFBBBFRRR".calculateSeatID == 119);
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assert("BBFFBBFRLL".calculateSeatID == 820);
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}
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auto findMissingSeatID(T)(T seats)
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{
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auto sortedSeatIDs = seats.map!calculateSeatID.array.sort;
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return sortedSeatIDs.zip(sortedSeatIDs.drop(1))
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.find!(seatPair => seatPair[1] - seatPair[0] != 1).front[0] + 1;
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}
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