Leetcode--Permutations II

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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].

思路：在Permutations的解法上，处理重复问题。

class Solution {public:    set<vector<int>> res;    void swap(int *a,int *b)    {        int temp=*a;        *a=*b;        *b=temp;    }    void function(vector<int>&num,int i)    {        if(i==num.size()-1)        {            res.insert(num);        }        else{            for(int j=i;j<num.size();j++)            {                if(j==i)                    function(num,i+1);                else if(j>i&&num[j]!=num[i]){                    swap(&num[i],&num[j]);                    function(num,i+1);                    swap(&num[i],&num[j]);                }            }        }    }    vector<vector<int> > permuteUnique(vector<int> &num) {        if(num.size()>0)            function(num,0);        vector<vector<int>> result(res.begin(),res.end());        return result;    }};

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