Hofstadter Figure-Figure sequences: Difference between revisions

=={{header|Java}}==

'''Code:'''

<lang java>import java.util.*;

class Hofstadter

{

private static List<Integer> getSequence(int rlistSize, int slistSize)

{

List<Integer> rlist = new ArrayList<Integer>();

List<Integer> slist = new ArrayList<Integer>();

Collections.addAll(rlist, 1, 3, 7);

Collections.addAll(slist, 2, 4, 5, 6);

List<Integer> list = (rlistSize > 0) ? rlist : slist;

int targetSize = (rlistSize > 0) ? rlistSize : slistSize;

while (list.size() > targetSize)

list.remove(list.size() - 1);

while (list.size() < targetSize)

{

int lastIndex = rlist.size() - 1;

int lastr = rlist.get(lastIndex).intValue();

int r = lastr + slist.get(lastIndex).intValue();

rlist.add(Integer.valueOf(r));

for (int s = lastr + 1; (s < r) && (list.size() < targetSize); s++)

slist.add(Integer.valueOf(s));

}

return list;

}

public static int ffr(int n)

{ return getSequence(n, 0).get(n - 1).intValue(); }

public static int ffs(int n)

{ return getSequence(0, n).get(n - 1).intValue(); }

public static void main(String[] args)

{

System.out.print("R():");

for (int n = 1; n <= 10; n++)

System.out.print(" " + ffr(n));

System.out.println();

Set<Integer> first40R = new HashSet<Integer>();

for (int n = 1; n <= 40; n++)

first40R.add(Integer.valueOf(ffr(n)));

Set<Integer> first960S = new HashSet<Integer>();

for (int n = 1; n <= 960; n++)

first960S.add(Integer.valueOf(ffs(n)));

for (int i = 1; i <= 1000; i++)

{

Integer n = Integer.valueOf(i);

if (first40R.contains(n) == first960S.contains(n))

System.out.println("Integer " + i + " either in both or neither set");

}

System.out.println("Done");

}

}</lang>

'''Output:'''

<pre>R(): 1 3 7 12 18 26 35 45 56 69

Done</pre>