1 #include<cstdio>
2 #include<vector>
3 #include<iostream>
4 #include<cstdlib>
5 #include<cstring>
6 using namespace std;
7 int in[30],out[30],vis[30];
8 int n;
9
10 vector<int> edge[27];
11
12 void dfs(int s){
13 vis[s]=1;
14 for(int i=0;i<edge[s].size();i++)
15 if(vis[edge[s][i]]==0)
16 dfs(edge[s][i]);
17 return ;
18 }
19
20 bool euler(int s){
21 int i;
22 memset(vis,0,sizeof(vis));
23 dfs(s);
24 for(i=0;i<26;i++){
25 if(vis[i]==0&&edge[i].size()!=0)
26 return false;
27 }
28 return true;
29 }
30
31 int main(){
32 int t,n,i,j,len;
33 char str[1010];
34 scanf("%d",&t);
35 while(t--){
36 scanf("%d",&n);
37 memset(in,0,sizeof(in));
38 memset(out,0,sizeof(out));
39 for(i=0;i<26;i++)
40 edge[i].clear();
41 while(n--){
42 cin>>str;
43 len=strlen(str);
44 len--;
45 out[str[0]-'a']++;
46 in[str[len]-'a']++;
47 edge[str[0]-'a'].push_back(str[len]-'a');
48 edge[str[len]-'a'].push_back(str[0]-'a');
49 }
50
51 //search the eulerian path
52 if(euler(str[0]-'a')==false){
53 cout<<"The door cannot be opened."<<endl;
54 continue;
55 }
56 int f1=0,f2=0;
57 for(i=0;i<26;i++){
58 if(in[i]!=out[i]){
59 if(in[i]<out[i]){
60 if(out[i]-in[i]==1&&f1==0)
61 f1=1;
62 else
63 break;
64 }
65 if(out[i]<in[i]){
66 if(in[i]-out[i]==1&&f2==0)
67 f2=1;
68 else
69 break;
70 }
71 }
72 }
73
74 if(i==26)
75 cout<<"Ordering is possible."<<endl;
76 else
77 cout<<"The door cannot be opened."<<endl;
78 }
79 return 0;
80 }
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