permutations.cpp

#include <iostream>
//---------------------
#include <algorithm>
#include <vector>
using namespace std;

class Solution {
  public:
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        vector<vector<int>> result;
        if (nums.size() == 1) {
            result.push_back(nums);
        } else {
            sort(nums.begin(), nums.end());
            int last_num;

            for (int i = 0; i < nums.size(); i++) {
                if (i > 0 && nums[i] == last_num) {
                    continue;
                } else {
                    last_num = nums[i];
                }
                int current = nums[i];
                vector<int> remain_nums = nums;
                remain_nums.erase(remain_nums.begin() + i);
                auto remain_permu = permuteUnique(remain_nums);
                for (int j = 0; j < remain_permu.size(); j++) {
                    remain_permu[j].insert(remain_permu[j].begin(), current);
                    result.push_back(remain_permu[j]);
                }
            }
        }
        return result;
    }
};
//---------------------

int main() {
    Solution s;
    vector<int> vec = {1, 1, 2};
    auto result = s.permuteUnique(vec);
    for (int i = 0; i < result.size(); i++) {
        for (int j = 0; j < result[i].size(); j++) {
            cout << result[i][j] << " ";
        }
        cout << endl;
    }

    return 0;
}