47.Permutations II

Tags: Medium Backtracking

Links: https://leetcode.com/problems/permutations-ii/

---

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

Example:

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

---

class Solution {
public:
    vector<vector<int>> permuteUnique(vector<int>& nums) {
        std::ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout.tie(NULL);

        sort(nums.begin(), nums.end());
        vector<vector<int>> res;
        do {
            res.push_back(nums);
        } while(next_permutation(nums.begin(), nums.end()));

        return res;
    }
};

这道题和46题的代码可以完全不变动就能AC，但是用DFS的方法会产生重复序列，嗯……能有简便方法就不去写麻烦的了。