[leetcode] 47. Permutations II

题目

Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order.

Example 1:

Input: nums = [1,1,2]
Output:
[[1,1,2],
 [1,2,1],
 [2,1,1]]

Example 2:

Input: nums = [1,2,3]
Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

Constraints:

• 1 <= nums.length <= 8
• -10 <= nums[i] <= 10

思路

全排列，注意去重的方法是每次插入序列的元素时，只遍历到重复值出现前即可。

代码

python版本：

class Solution:
    def permuteUnique(self, nums: List[int]) -> List[List[int]]:
        res = [[]]
        for n in range(len(nums)):
            res = [r[:i]+[nums[n]]+r[i:] for r in res for i in range((r+[n]).index(n)+1)]
        return res