LeetCode 46 - Permutations

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Permutations

Given a collection of distinct numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:
[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

My Code

class Solution {public:    void doPermute(vector<vector<int> >& res, vector<int> r, vector<int> v)    {        int size = v.size();        if (size == 1)        {            r.push_back(v[0]);            res.push_back(r);            return;        }        for (int i = 0; i < size; i++)        {            vector<int> rr(r);            vector<int> vv(v);            rr.push_back(v[i]);            vv.erase(vv.begin() + i);            doPermute(res, rr, vv);        }    }    vector<vector<int> > permute(vector<int>& nums) {        vector<vector<int> > res;        vector<int> r;        vector<int> v(nums);        doPermute(res, r, v);        return res;    }};

Runtime: 20 ms

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