RosettaCodeData/Task/Knights-tour/SequenceL/knights-tour.sequencel
2017-09-25 22:28:19 +02:00

50 lines
1.8 KiB
Text

import <Utilities/Sequence.sl>;
import <Utilities/Conversion.sl>;
main(args(2)) :=
let
N := stringToInt(args[1]) when size(args) > 0 else 8;
M := stringToInt(args[2]) when size(args) > 1 else N;
startX := stringToInt(args[3]) when size(args) > 2 else 1;
startY := stringToInt(args[4]) when size(args) > 3 else 1;
board[i,j] := 0 foreach i within 1 ... N, j within 1 ... M;
spacing := size(toString(N*M)) + 1;
in
join(printRow(
tour(setBoard(board, startX, startX, 1), [startX,startY], 2),
spacing));
potentialMoves := [[2,1], [2,-1], [1,2], [1,-2], [-1,2], [-1,-2], [-2,1], [-2,-1]];
printRow(row(1), spacing) := join(printSquare(row, spacing)) ++ "\n";
printSquare(val, spacing) :=
let
str := toString(val);
in
duplicate(' ', spacing - size(str)) ++ str;
tour(board(2), current(1), move) :=
let
validMoves := validMove(board, current + potentialMoves);
numMoves[i] := size(validMove(board, validMoves[i] + potentialMoves));
chosenMove := minPosition(numMoves);
in
board when move > size(board) * size(board[1]) else
[] when size(validMoves) = 0 else
[] when move < size(board) * size(board[1]) and numMoves[chosenMove] = 0 else
tour(setBoard(board, validMoves[chosenMove][1], validMoves[chosenMove][2], move), validMoves[chosenMove], move + 1);
validMove(board(2), position(1)) :=
(position when board[position[1], position[2]] = 0)
when position[1] >= 1 and position[1] <= size(board) and position[2] >= 1 and position[2] <= size(board);
minPosition(x(1)) := minPositionHelper(x, 2, 1, x[1]);
minPositionHelper(x(1), i, minPos, minVal) :=
minPos when i > size(x) else
minPositionHelper(x, i + 1, minPos, minVal) when x[i] > minVal else
minPositionHelper(x, i + 1, i, x[i]);
setBoard(board(2), x, y, value)[i,j] :=
value when x = i and y = j else
board[i,j] foreach i within 1 ... size(board), j within 1 ... size(board[1]);