204 lines
3.8 KiB
D
204 lines
3.8 KiB
D
import std;
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void main()
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{
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File("input", "r").byLineCopy.array.calculateNumberOfOccupiedSeatsStable.writeln;
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}
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auto calculateValidNeighbouringSeatPositions(size_t i, size_t j, size_t height, size_t width)
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{
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return [
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tuple(i - 1, j - 1), tuple(i - 1, j), tuple(i - 1, j + 1), tuple(i,
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j - 1), tuple(i, j + 1), tuple(i + 1, j - 1), tuple(i + 1, j),
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tuple(i + 1, j + 1)
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].filter!(position => position[0] >= 0 && position[0] < height
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&& position[1] >= 0 && position[1] < width);
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}
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auto calculateNewSeatState(const char seat, ulong numberOfOccupiedNeighbouringSeats)
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{
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if (seat == '#' && numberOfOccupiedNeighbouringSeats >= 4)
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{
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return 'L';
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}
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else if (seat == 'L' && numberOfOccupiedNeighbouringSeats == 0)
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{
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return '#';
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}
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else
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{
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return seat;
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}
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}
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auto calculateNextSeatOccupation(const char[][] seats)
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{
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if (seats.empty || seats.front.empty)
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{
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return seats;
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}
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immutable height = seats.length;
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immutable width = seats.front.length;
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return seats.enumerate.map!((indexedRow) {
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immutable i = indexedRow.index;
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const row = indexedRow.value;
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return row.byChar.enumerate.map!((indexedSeat) {
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immutable j = indexedSeat.index;
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immutable seat = indexedSeat.value;
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immutable numberOfOccupiedNeighbouringSeats = calculateValidNeighbouringSeatPositions(i,
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j, height, width).map!(position => seats[position[0]][position[1]])
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.filter!(it => it == '#')
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.count;
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return seat.calculateNewSeatState(numberOfOccupiedNeighbouringSeats);
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}).array;
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}).array;
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}
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unittest
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{
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auto input = `L.LL.LL.LL
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LLLLLLL.LL
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L.L.L..L..
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LLLL.LL.LL
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L.LL.LL.LL
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L.LLLLL.LL
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..L.L.....
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LLLLLLLLLL
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L.LLLLLL.L
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L.LLLLL.LL`.dup.split("\n");
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assert(input.calculateNextSeatOccupation.join("\n") == `#.##.##.##
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#######.##
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#.#.#..#..
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####.##.##
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#.##.##.##
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#.#####.##
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..#.#.....
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##########
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#.######.#
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#.#####.##`);
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}
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unittest
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{
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auto input = `#.##.##.##
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#######.##
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#.#.#..#..
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####.##.##
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#.##.##.##
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#.#####.##
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..#.#.....
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##########
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#.######.#
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#.#####.##`.dup.split("\n");
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assert(input.calculateNextSeatOccupation.join("\n") == `#.LL.L#.##
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#LLLLLL.L#
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L.L.L..L..
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#LLL.LL.L#
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#.LL.LL.LL
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#.LLLL#.##
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..L.L.....
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#LLLLLLLL#
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#.LLLLLL.L
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#.#LLLL.##`);
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}
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unittest
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{
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auto input = `#.LL.L#.##
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#LLLLLL.L#
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L.L.L..L..
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#LLL.LL.L#
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#.LL.LL.LL
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#.LLLL#.##
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..L.L.....
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#LLLLLLLL#
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#.LLLLLL.L
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#.#LLLL.##`.dup.split("\n");
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assert(input.calculateNextSeatOccupation.join("\n") == `#.##.L#.##
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#L###LL.L#
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L.#.#..#..
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#L##.##.L#
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#.##.LL.LL
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#.###L#.##
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..#.#.....
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#L######L#
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#.LL###L.L
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#.#L###.##`);
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}
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unittest
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{
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auto input = `#.##.L#.##
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#L###LL.L#
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L.#.#..#..
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#L##.##.L#
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#.##.LL.LL
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#.###L#.##
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..#.#.....
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#L######L#
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#.LL###L.L
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#.#L###.##`.dup.split("\n");
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assert(input.calculateNextSeatOccupation.join("\n") == `#.#L.L#.##
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#LLL#LL.L#
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L.L.L..#..
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#LLL.##.L#
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#.LL.LL.LL
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#.LL#L#.##
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..L.L.....
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#L#LLLL#L#
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#.LLLLLL.L
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#.#L#L#.##`);
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}
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unittest
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{
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auto input = `#.#L.L#.##
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#LLL#LL.L#
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L.L.L..#..
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#LLL.##.L#
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#.LL.LL.LL
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#.LL#L#.##
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..L.L.....
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#L#LLLL#L#
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#.LLLLLL.L
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#.#L#L#.##`.dup.split("\n");
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assert(input.calculateNextSeatOccupation.join("\n") == `#.#L.L#.##
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#LLL#LL.L#
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L.#.L..#..
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#L##.##.L#
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#.#L.LL.LL
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#.#L#L#.##
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..L.L.....
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#L#L##L#L#
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#.LLLLLL.L
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#.#L#L#.##`);
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}
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auto calculateNumberOfOccupiedSeatsStable(const char[][] seats)
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{
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return recurrence!((seats, n) => seats[n - 1].calculateNextSeatOccupation)(seats).slide(2)
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.map!array
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.find!((pair) => pair[0] == pair[1])
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.front
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.front
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.join
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.filter!(seat => seat == '#')
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.count;
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}
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unittest
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{
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auto input = `L.LL.LL.LL
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LLLLLLL.LL
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L.L.L..L..
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LLLL.LL.LL
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L.LL.LL.LL
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L.LLLLL.LL
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..L.L.....
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LLLLLLLLLL
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L.LLLLLL.L
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L.LLLLL.LL`.dup.split("\n");
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assert(input.calculateNumberOfOccupiedSeatsStable == 37);
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}
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