【回溯】47. Permutations II

注意删除重复元素：

class Solution {
public:
    vector<vector<int>> ans;
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        vector<int> temp;
        sort(nums.begin(),nums.end());
        find(nums,0);
        return ans;
    }
   
    bool can(vector<int> &nums,int begin,int end)
    {
        for(int i=begin;i<end;i++)
        {
            if(nums[i]==nums[end])
                return 0;
        }
        return 1;
    }
    void find(vector<int> nums,int start)
    {
        if(start==nums.size())
        {
            ans.push_back(nums);
            return ;
        }
        else
        {
            for(int i=start;i<nums.size();i++)  //每个数字只能用一遍
            {
             //   if(i>start&&nums[i]==nums[i-1])
                  //  continue;
               if(!can(nums,start,i))  //避开重复元素
                   continue;
                int temp=nums[start];
                nums[start]=nums[i];
                nums[i]=temp;

                find(nums,start+1);


                temp=nums[start];
                nums[start]=nums[i];
                nums[i]=temp;                 
                
            }
        }
    }
    
};