LeetCode - 47. Permutations II

采用46. Permutation中的第二种字典序的方法的话，会自动去除重复的list，所以可以直接把46的解法二直接拿过来，代码如下：

public class Solution{
List<List<Integer>> result = new ArrayList<List<Integer>>();

public int factorial(int x){
return (x == 0) || (x == 1) ? 1 : factorial(x - 1) * x;
}

public void nextPermutation(int[] nums){
int i = nums.length - 1;
while(i > 0 && nums[i] <= nums[i - 1]){
i--;
}
if(i <= 0) return;

int j = nums.length - 1;
while(j >= i && nums[j] <= nums[i - 1]){
j--;
}

int temp = nums[i - 1];
nums[i - 1] = nums[j];
nums[j] = temp;

int l = i;
int r = nums.length - 1;
while(l < r){
temp = nums[l];
nums[l] = nums[r];
nums[r] = temp;
l++;
r--;
}

List<Integer> list = new ArrayList<Integer>();
for(int x : nums){
list.add(x);
}
result.add(list);
}

public List<List<Integer>> permuteUnique(int[] nums){
// Corner case
if(nums == null || nums.length == 0){
return result;
}

// Sort nums
Arrays.sort(nums);

// Convert nums to list
List<Integer> list = new ArrayList<Integer>();
for(int x : nums){
list.add(x);
}
result.add(list);

// Add next permutation iterativel
for(int i = 1; i < factorial(nums.length); i++){
nextPermutation(nums);
}

return result;
}
}