Problems:

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

For example,

[1,1,2] have the following unique permutations:

[1,1,2], [1,2,1], and [2,1,1].

解法一：STL中的next_permutation

class Solution {public:    vector
     
      
       > permuteUnique(vector
       
        & nums) {        vector
        
         
          > result;                sort(nums.begin(),nums.end());        do{            result.push_back(nums);        }while(next_permutation(nums.begin(),nums.end()));                return result;            }};