题解 | #数组中未出现的最小正整数#

class Solution {
public:
    vector<int> res;
    vector<vector<int>> ans;
    vector<bool> isUsed;
    void backtracking(vector<int> &num){
        if(res.size() == num.size()){
             ans.push_back(res);
            return;
        }
        for(int i = 0; i < num.size();++i){
            if(isUsed[i] == true || (i >= 1 && num[i] == num[i-1] && isUsed[i-1] == false))continue;
            isUsed[i] = true;
            res.push_back(num[i]);
            backtracking(num);
            res.pop_back();
            isUsed[i] = false;
        }
    }
    vector<vector<int> > permuteUnique(vector<int> &num) {
        sort(num.begin(),num.end());
        isUsed.resize(num.size(),false);
        backtracking(num);
        return ans;
    }
};