47. Permutations II

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LeetCode

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class Solution {
    public List<List<Integer>> permuteUnique(int[] nums) {
        List<List<Integer>> output =new LinkedList();
		List<Integer> nums_lst=new ArrayList<Integer>();
		
		for(int num:nums) nums_lst.add(num);
		backtrack(nums.length,nums_lst,output,0);  
		return output;
	}
	
	static void backtrack(int n, List<Integer> nums_lst, List<List<Integer>> output, int first){				
		if (first==n) {
			if(!output.contains(nums_lst))output.add(new ArrayList<Integer>(nums_lst));
			}
        for (int i = first; i < n; i++) {
            Collections.swap(nums_lst, first, i);				
            backtrack(n, nums_lst, output, first + 1);	
            Collections.swap(nums_lst, first, i);
        }
    }
}
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