Permutations

问题：全排列

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;

    }

};