leetcode47 全排列

code

实际上是在原来的全排列种做了去重的处理，其余的方法大同小异。值得一提的是，第19行的return如果不加的话多少还是会影响性能的。

//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
    
    

    boolean[] vis;
    List<List<Integer>> res = new ArrayList<>();
    
    public List<List<Integer>> permuteUnique(int[] nums) {
    
    
        List<Integer> path = new ArrayList<>();
        vis = new boolean[nums.length];
        Arrays.sort(nums);
        getPermutation(0, nums, path);
        return res;
    }

    private void getPermutation(int steps, int[] nums, List<Integer> path){
    
    

        if (steps == nums.length){
    
    
            res.add(new ArrayList<Integer>(path));
            return;
        }

        for (int i = 0; i < nums.length; i++) {
    
    
            if (vis[i] || (i > 0 && nums[i] == nums[i - 1] && !vis[i - 1])){
    
    
                continue;
            }
            path.add(nums[i]);
            vis[i] = true;
            getPermutation(steps + 1, nums, path);
            vis[i] = false;
            path.remove(steps);
        }
    }
}
//leetcode submit region end(Prohibit modification and deletion)