Data update

Task/Dominoes/Java/dominoes-2.java

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+import java.math.BigInteger;
+
+public final class DominosExtraCredit {
+
+	public static void main(String[] args) {
+		BigInteger arrangements = BigInteger.valueOf(dominoTilingCount(7, 8));
+		BigInteger permutations = factorial(BigInteger.valueOf(28));
+		BigInteger flips = BigInteger.TWO.pow(28);
+		
+		System.out.println("Arrangements ignoring values: " + arrangements);
+		System.out.println("Permutations of 28 dominos: " + permutations);
+		System.out.println("Permuted arrangements ignoring flipping dominos: "
+						   + permutations.multiply(arrangements));
+		System.out.println("Possible flip configurations: " + flips);
+		System.out.println("Possible permuted arrangements with flips: "
+						   + permutations.multiply(flips).multiply(arrangements));
+	}
+	
+	private static int dominoTilingCount(int rows, int cols) {
+	    double product = 1.0;
+	    for ( int i = 1; i <= ( rows + 1 ) / 2; i++ ) {
+	    	for ( int j = 1; j <= ( cols + 1 ) / 2; j++ ) {
+	    		final double cosRows = Math.cos(Math.PI * i / ( rows + 1 ));
+	    		final double cosCols = Math.cos(Math.PI * j / ( cols + 1 ));
+	    		product *= ( cosRows * cosRows + cosCols * cosCols ) * 4;
+	    	}
+	    }
+	    return (int) product;
+	}
+	
+	private static BigInteger factorial(BigInteger number) {
+		if ( number.equals(BigInteger.TWO) ) {
+			return number;
+		}
+		return number.multiply(factorial(number.subtract(BigInteger.ONE)));
+	}
+
+}