32 lines
801 B
Java
32 lines
801 B
Java
|
import java.util.Arrays;
|
||
|
|
|
||
|
|
public class SetPartitions {
|
||
|
|
|
||
|
|
public static int[][] generateSetPartitions(int n) {
|
||
|
|
if (n == 1)
|
||
|
|
return new int[][]{{0}};
|
||
|
|
int[][] p = generateSetPartitions(n - 1);
|
||
|
|
int[] m = new int[p.length];
|
||
|
|
int len = 0;
|
||
|
|
for (int i = 0; i < p.length; i++) {
|
||
|
|
for (int v : p[i])
|
||
|
|
m[i] = Math.max(m[i], 1 + v);
|
||
|
|
len += m[i] + 1;
|
||
|
|
}
|
||
|
|
int[][] res = new int[len][n];
|
||
|
|
for (int i = 0, pos = 0; i < p.length; i++) {
|
||
|
|
for (int j = 0; j <= m[i]; j++, pos++) {
|
||
|
|
System.arraycopy(p[i], 0, res[pos], 0, n - 1);
|
||
|
|
res[pos][n - 1] = (i % 2 == 1 ? j + 1 : m[i] - j + 1) % (m[i] + 1);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return res;
|
||
|
|
}
|
||
|
|
|
||
|
|
// Usage example
|
||
|
|
public static void main(String[] args) {
|
||
|
|
for (int i = 1; i < 5; i++)
|
||
|
|
System.out.println(Arrays.deepToString(generateSetPartitions(i)));
|
||
|
|
}
|
||
|
|
}
|