47. 全排列 II
给定一个可包含重复数字的序列 nums ,按任意顺序 返回所有不重复的全排列。
示例 1:
输入:nums = [1,1,2]
输出:
[[1,1,2],
[1,2,1],
[2,1,1]]
示例 2:
输入:nums = [1,2,3]
输出:[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
提示:
1 <= nums.length <= 8
-10 <= nums[i] <= 10
class Solution {
private List<List<Integer>> ans = new ArrayList<>();
public List<List<Integer>> permuteUnique(int[] nums) {
Arrays.sort(nums);
int len = nums.length;
boolean[] used = new boolean[len];
Deque<Integer> path = new LinkedList<>();
dfs(nums, path, used, 0);
return ans;
}
private void dfs(int[] nums, Deque<Integer> path, boolean[] used, int index) {
if (index == nums.length) {
ans.add(new ArrayList<>(path));
return;
}
for (int i = 0; i < nums.length; i++) {
if (used[i] || (i > 0 && !used[i - 1] && nums[i] == nums[i - 1]))
continue;
used[i] = true;
path.add(nums[i]);
dfs(nums, path, used, index + 1);
path.removeLast();
used[i] = false;
}
}
}