# 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
## template
```java
class Solution {
List> ans = new ArrayList<>();
public List> permuteUnique(int[] nums) {
dfs(nums, 0);
return ans;
}
private void dfs(int[] nums, int cur) {
if (cur == nums.length) {
List line = new ArrayList<>();
for (int i : nums) {
line.add(i);
}
ans.add(line);
} else {
for (int i = cur; i < nums.length; i++) {
if (canSwap(nums, cur, i)) {
swap(nums, cur, i);
dfs(nums, cur + 1);
swap(nums, cur, i);
}
}
}
}
private boolean canSwap(int nums[], int begin, int end) {
for (int i = begin; i < end; i++) {
if (nums[i] == nums[end]) {
return false;
}
}
return true;
}
private void swap(int nums[], int i, int j) {
int temp = nums[i];
nums[i] = nums[j];
nums[j] = temp;
}
}
```
## 答案
```java
```
## 选项
### A
```java
```
### B
```java
```
### C
```java
```