Data commit

Task/Padovan-sequence/Java/padovan-sequence.java

@@ -0,0 +1,69 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public final class Padovan {
+
+	public static void main(String[] aArgs) {
+		for ( int i = 0; i < 64; i++ ) {
+			recurrences.add(padovanRecurrence(i));
+			floors.add(padovanFloor(i));
+		}		
+		
+		System.out.println("The first 20 terms of the Padovan sequence:");
+		recurrences.subList(0, 20).forEach( term -> System.out.print(term + " ") );		
+		System.out.println(System.lineSeparator());
+		
+		System.out.print("Recurrence and floor functions agree for first 64 terms? " + recurrences.equals(floors));
+		System.out.println(System.lineSeparator());
+		
+		List<String> words = createLSystem();		
+		
+		System.out.println("The first 10 terms of the L-system:");
+		words.subList(0, 10).forEach( term -> System.out.print(term + " ") );		
+		System.out.println(System.lineSeparator());
+		
+		System.out.print("Length of first 32 terms produced from the L-system match Padovan sequence? ");		
+		List<Integer> wordLengths = words.stream().map( s -> s.length() ).toList();
+		System.out.println(wordLengths.equals(recurrences.subList(0, 32)));
+	}
+	
+	private static int padovanRecurrence(int aN) {
+		return ( aN <= 2 ) ? 1 : recurrences.get(aN - 2) + recurrences.get(aN - 3);		
+	}
+	
+	private static int padovanFloor(int aN) {
+		return (int) Math.floor(Math.pow(PP, aN - 1) / SS + 0.5);
+	}
+	
+	private static List<String> createLSystem() {
+		List<String> words = new ArrayList<String>();		
+		StringBuilder stringBuilder = new StringBuilder();
+		String text = "A";
+		
+		do {
+			words.add(text);
+			stringBuilder.setLength(0);
+			for ( char ch : text.toCharArray() ) {
+				String entry = switch ( ch ) {
+					case 'A' -> "B";
+					case 'B' -> "C";
+					case 'C' -> "AB";
+					default -> throw new AssertionError("Unexpected character found: " + ch);
+				};
+				
+				stringBuilder.append(entry);
+			}
+			
+			text = stringBuilder.toString();
+		} while ( words.size() < 32 );
+		
+		return words;
+	}
+	
+	private static List<Integer> recurrences = new ArrayList<Integer>();
+	private static List<Integer> floors = new ArrayList<Integer>();
+	
+	private static final double PP = 1.324717957244746025960908854;
+	private static final double SS = 1.0453567932525329623;
+
+}