Data Update

Task/Curzon-numbers/Java/curzon-numbers.java

@@ -0,0 +1,48 @@
+public final class CurzonNumbers {
+
+	public static void main(String[] aArgs) {
+		for ( int k = 2; k <= 10; k += 2 ) {
+	        System.out.println("Generalised Curzon numbers with base " + k + ":");
+	        int n = 1;
+	        int count = 0;
+	        while ( count < 50 ) {
+	            if ( isGeneralisedCurzonNumber(k, n) ) {
+	                System.out.print(String.format("%4d%s", n, ( ++count % 10 == 0 ? "\n" : " " )));
+	            }
+	            n += 1;
+	        }
+	
+	        while ( count < 1_000 ) {
+	        	if ( isGeneralisedCurzonNumber(k, n) ) {
+	        		count += 1;
+	        	}
+	        	n += 1;
+	        }	
+	        System.out.println("1,000th Generalised Curzon number with base " + k + ": " + ( n - 1 ));
+	        System.out.println();
+	    }
+	}
+	
+	private static boolean isGeneralisedCurzonNumber(int aK, int aN) {
+	    final long r = aK * aN;
+	    return modulusPower(aK, aN, r + 1) == r;
+	}
+	
+	private static long modulusPower(long aBase, long aExponent, long aModulus) {
+	    if ( aModulus == 1 ) {
+	        return 0;
+	    }	
+	
+	    aBase %= aModulus;
+	    long result = 1;
+	    while ( aExponent > 0 ) {
+	        if ( ( aExponent  & 1 ) == 1 ) {
+	            result = ( result * aBase ) % aModulus;
+	        }
+	        aBase = ( aBase * aBase ) % aModulus;
+	        aExponent >>= 1;
+	    }
+	    return result;
+	}
+
+}