leetcode-Permutations

Difficulty: Medium

[1,2,3]

[1,2,3]

[1,3,2]

[2,1,3]

[2,3,1]

[3,1,2]

[3,2,1]

class Solution {
vector<vector<int> > res;
void helper(vector<int> &nums,int n,int cur){
if(cur==n){
res.push_back(nums);
return;
}
for(int i=cur;i<n;++i){
if(cur!=i)
swap(nums[cur],nums[i]);
helper(nums,n,cur+1);
if(cur!=i)
swap(nums[cur],nums[i]);
}

}

public:
vector<vector<int>> permute(vector<int>& nums) {
if(nums.empty())
return res;
helper(nums,nums.size(),0);
return res;
}
};