leetcode-90. Subsets II
90. Subsets II
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.
For example,
If nums = [1,2,2]
, a solution
is:
[ [2], [1], [1,2,2], [2,2], [1,2], [] ]
和上一题Subsets不同的就是这个集合里的元素是可以重复的。
在第一题的基础上,排序过后,相同的元素都是相邻的,只要过滤掉相同的即可
class Solution { public List<List<Integer>> subsetsWithDup(int[] nums) { List<List<Integer>> list = new ArrayList<>(); Arrays.sort(nums); backtrack(list, new ArrayList<>(), nums, 0); return list; } private void backtrack(List<List<Integer>> list, List<Integer> tempList, int [] nums, int start){ list.add(new ArrayList<>(tempList)); for(int i = start; i < nums.length; i++){ if(i > start && nums[i] == nums[i-1]) continue; // skip duplicates tempList.add(nums[i]); backtrack(list, tempList, nums, i + 1); tempList.remove(tempList.size() - 1); } } }
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还是不理解,,埋个坑,以后填