Permutations

问题：全排列

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

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;     } };