1 #include<iostream>
 2 #include<stack>
 3 #include<queue>
 4 using namespace std;
 5 int n;
 6 int ans[12];
 7 int visited[12]={0};
 8 typedef struct point{
 9     int num;
10 }Point;
11 stack< queue<Point> > mainstack;
12 void DFS()
13 {
14
15     int cur=1;
16     queue<Point> oneq;
17     for(int i=1;i<=n;i++)
18     {
19         Point oneP;
20         oneP.num=i;
21         oneq.push(oneP);
22     }
23     mainstack.push(oneq);
24     while(!mainstack.empty())
25     {
26         queue<Point> twoq;
27         twoq=mainstack.top();mainstack.pop();
28         if(!twoq.empty())
29         {
30             Point twoP=twoq.front();twoq.pop();
31             int onenum=twoP.num;
32             visited[ans[cur]]=0;//1.如果要修改则将当前置为可用
33             ans[cur]=onenum;
34             visited[onenum]=1;
35             queue<Point> threeq;//该节点的子节点
36             for(int i=1;i<=n;i++)
37             {
38                 if(visited[i]==0)
39                 {
40                     Point threep;
41                     threep.num=i;//threep.flag=i;
42                     threeq.push(threep);
43                 }
44             }
45             //在这里直接加空判断，会出现本节点兄弟为空，儿子不为空的情况
46             mainstack.push(twoq);
47             //没有可扩展节点
48             if(threeq.empty())
49             {
50                 for(int i=1;i<=n;i++)
51                     cout<<ans[i]<<" ";
52                 cout<<endl;
53             }
54             else
55             {
56                 mainstack.push(threeq);
57                 cur++;
58             }
59         }
60         else
61         {
62             visited[ans[cur]]=0;
63             ans[cur]=0;//这里置0才能完全还原
64             cur--;
65         }
66     }
67 }
68 int main()
69 {
70     cin>>n;
71     DFS();
72     return 0;
73 }