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import static org.junit.Assert.assertSame;
public class Subsets {
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> result = new ArrayList<List<Integer>>();
if (nums == null || nums.length == 0) {
return result;
}
Arrays.sort(nums);
helper(0, result, new ArrayList<Integer>(), nums);
return result;
}
private void helper(int start, List<List<Integer>> result, List<Integer> crt, int[] nums) {
if (start >= nums.length) {
result.add(crt);
return;
}
helper(start + 1, result, new ArrayList<Integer>(crt), nums);
crt.add(nums[start]);
helper(start + 1, result, new ArrayList<Integer>(crt), nums);
}
@Test
public void test() {
int[] nums = new int[]{1, 2, 3};
List<List<Integer>> result = subsets(nums);
assertSame(8, result.size());
}
}
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