leetcode

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],  [3,2,1]]

class Solution {public:    vector<vector<int>> permute(vector<int>& nums) {        vector<vector<int> >res;        vector<int> out;        vector<int> visited(nums.size(),0);        permuteDFS(nums,0,visited,res,out);        return res;    }    void permuteDFS(vector<int>& nums,int level,vector<int> &visited,vector<vector<int> >&res,vector<int> &out){        if(level==nums.size()) res.push_back(out);        else        {            for(int i=0;i<nums.size();i++)            {                if(visited[i]==0)                {                    visited[i]=1;                    out.push_back(nums[i]);                    permuteDFS(nums,level+1,visited,res,out);                    out.pop_back();                    visited[i]=0;                }            }        }    }};