« back

Permutations II

Tags : array, backtracking, leetcode, cpp, medium

Problem Statement - link #

Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order.

Examples #

Example 1:

Input: nums = [1,1,2]
Output:
[[1,1,2],
 [1,2,1],
 [2,1,1]]

Example 2:

Input: nums = [1,2,3]
Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

Constraints #

Solutions #

class Solution {
public:
    set<vector<int>> s;    
    void rc(vector<int>& nums, int i){
        if(i == nums.size()-1){
            s.insert(nums); 
            return ;
        }
        for(int j=i; j<nums.size(); j++){
            swap(nums[j],nums[i]);
            rc(nums,i+1);
            swap(nums[j],nums[i]);
        }
    }
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        vector<vector<int>> res;
        rc(nums, 0);
        for(auto i: s) res.push_back(i);
        return res;
    }
};