https://leetcode.com/problems/subsets/
这两道取子集的题目基本上也没什么好讲的，基本的回溯方法即可，处理方式同排列和组合系列。
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public List<List<Integer>> subsets(int[] nums) {
if (nums == null || nums.length == 0) {
return new ArrayList<>();
}
List<List<Integer>> result = new ArrayList<>();
handle(nums, 0, new ArrayList<>(), result);
return result;
}
private void (int[] nums, int start, List<Integer> cur, List<List<Integer>> result) {
result.add(new ArrayList<>(cur));
for (int i = start; i < nums.length; i++) {
cur.add(nums[i]);
handle(nums, i + 1, cur, result);
cur.remove(cur.size() - 1);
}
}
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90. Subsets II
https://leetcode.com/problems/subsets-ii/
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public List<List<Integer>> subsetsWithDup(int[] nums) {
if (nums == null || nums.length == 0) {
return new ArrayList<>();
}
List<List<Integer>> result = new ArrayList<>();
Arrays.sort(nums);
handle(nums, 0, new ArrayList<>(), result);
return result;
}
private void (int[] nums, int start, List<Integer> cur, List<List<Integer>> result) {
result.add(new ArrayList<>(cur));
for (int i = start; i < nums.length; i++) {
if (i > start && nums[i] == nums[i - 1]) {
continue;
}
cur.add(nums[i]);
handle(nums, i + 1, cur, result);
cur.remove(cur.size() - 1);
}
}
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