Permutations

class Solution {
public:
void swap(int &a, int &b)
{
int temp;
temp=a;
a=b;
b=temp;
}

void permutation(vector<int>& nums, vector<vector<int>>& res, int n)
{
if(n==nums.size()-1)
{
res.push_back(nums);
return;
}
for(int i=n;i<nums.size();i++)
{
swap(nums[i],nums
);
permutation(nums,res,n+1);
swap(nums[i],nums
);
}

}

vector<vector<int>> permute(vector<int>& nums) {
vector<vector<int>> res;
if(nums.size()==0)
return res;
permutation(nums,res,0);
return res;
}
};