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SubsetsII.java
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SubsetsII.java
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package leetcode;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class SubsetsII {
public List<List<Integer>> subsetsWithDup(int[] nums) {
Map<List<Integer>, List<Integer>> result = new HashMap<>();
List<Integer> current = new ArrayList<>();
// first sort
quickSort(0, nums.length - 1, nums);
subsets(nums, 0, current, result);
return new ArrayList<>(result.values());
}
private void quickSort(int s, int e, int[] nums) {
if (s >= e) {
return;
}
int p = part(s, e, nums);
quickSort(s, p - 1, nums);
quickSort(p + 1, e, nums);
}
private int part(int s, int e, int[] nums) {
int pivot = nums[e];
int i = s;
for (int j = s; j < e; j++) {
if (pivot > nums[j]) {
swap(nums, i, j);
i++;
}
}
swap(nums, i, e);
return i;
}
public void swap(int[] nums, int i, int j) {
if (i == j) {
return;
}
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}
private void subsets(int[] nums, int i, List<Integer> current,
Map<List<Integer>, List<Integer>> result) {
if (i == nums.length) {
List<Integer> tmp = new ArrayList<>(current);
result.put(tmp, tmp);
} else {
current.add(nums[i]);
subsets(nums, i + 1, current, result);
current.remove(current.size() - 1);
subsets(nums, i + 1, current, result);
}
}
}