Leetcode 90: subset II

link
subject ：

Ideas ： to flash back （ Elements can be duplicated and cannot be checked ）

And A subset of The difference is that the elements given by the title are repeated , If you follow the previous practice, the answer will be repeated ：

Here, you need to add conditions for selection to trim nodes ！
① If there are repeating elements, you have to Sort ！, Let the same element lean against ⼀ rise ,
② If you find that nums[i] == nums[i-1] be skip ！ meanwhile i>start

Java Realization ：

class Solution {
    
    List<List<Integer>> res=new LinkedList<>();
    LinkedList<Integer> path=new LinkedList<>();
    public List<List<Integer>> subsetsWithDup(int[] nums) {
    
        Arrays.sort(nums);
        dfs(nums,0);
        return res;
    }

    void dfs(int[] nums,int start){
    
        res.add(new LinkedList(path));
        for(int i=start;i<nums.length;i++){
    
            // To make a choice 
            // trim , Adjacent nodes with the same value are traversed only once 
            if(i>start && nums[i]==nums[i-1]){
     // i>start !
                continue;
            }
            path.add(nums[i]);
            dfs(nums,i+1);
            // revoke 
            path.removeLast();
        }
    }
}

Be careful ：i >start !