90. Subsets II
Tags: ‘Array’, ‘Backtracking’
Given a collection of integers that might contain duplicates, nums, return all possible subsets (the power set).
Note: The solution set must not contain duplicate subsets.
Example:
Input: [1,2,2] Output: [ [2], [1], [1,2,2], [2,2], [1,2], [] ]
Solution
用backtrack模板，注意termination， 剪枝trimming 98% 100%
```java
public List<List
private void backtrack(List<List<Integer>> result, List<Integer> temp, int[] nums, int start) {
result.add(new ArrayList<>(temp)); // 没有termination，需要所有subset
for(int i = start; i < nums.length; i++) {
if (i > start && nums[i] == nums[i-1]) {
continue; // skip duplicates
}
temp.add(nums[i]);
backtrack(result, temp, nums, i+1);
temp.remove(temp.size() - 1);
}
}
```