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