Padovan sequence: Difference between revisions
→{{header|Java}}
Line 1,268:
<syntaxhighlight>
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;
}
</syntaxhighlight>
{{ out }}
<pre>
The first 20 terms of the Padovan sequence:
1 1 1 2 2 3 4 5 7 9 12 16 21 28 37 49 65 86 114 151
Recurrence and floor functions agree for first 64 terms? true
The first 10 terms of the L-system:
A B C AB BC CAB ABBC BCCAB CABABBC ABBCBCCAB
Length of first 32 terms produced from the L-system match Padovan sequence? true
</pre>
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