lintcode: Permutations II

Given a list of numbers with duplicate number in it. Find all unique permutations.

可以见我的博文​​全排列实现​​

class Solution {
public:
    /**
     * @param nums: A list of integers.
     * @return: A list of unique permutations.
     */
    vector<vector<int> >res;

    void dfs(vector<int> &nums,vector<int> &sub,int cur){
        if(cur==nums.size()){
            res.push_back(sub);
            return;
        }

        for(int i=0;i<nums.size();i++){
            if(i==0||nums[i]!=nums[i-1]){
                int c1=0,c2=0;
                for(int j=0;j<nums.size();j++){
                    if(nums[j]==nums[i]){
                        c1++;
                    }
                }

                for(int j=0;j<cur;j++){
                    if(sub[j]==nums[i]){
                        c2++;
                    }
                }

                if(c2<c1){
                    sub[cur]=nums[i];
                    dfs(nums,sub,cur+1);
                }

            }
        }
    }

    vector<vector<int> > permuteUnique(vector<int> &nums) {
        // write your code here

        int len=nums.size();

        if(len==0){
            return res;
        }
        sort(nums.begin(),nums.end());
        vector<int> sub(len);

        dfs(nums,sub,0);

        return res;
    }
};