class Solution {public:    void dfs(vector<int> &num,vector<int> &vec2,vector<vector<int> >&vec1,int step,int vis[])    {        if(step==num.size())        {            vec1.push_back(vec2);            return ;        }        for(int i=0;i<num.size();i++)        {            int t=num[i];            if(vis[i]==0)            {                vis[i]=1;                vec2.push_back(t);                dfs(num,vec2,vec1,step+1,vis);                vec2.pop_back();                vis[i]=0;            }        }    }    vector<vector<int> > permute(vector<int> &num) {        vector<vector<int> > vec1;        vector<int> vec2;        int vis[100];        memset(vis,0,sizeof(vis));        dfs(num,vec2,vec1,0,vis);        return vec1;    }};