POJ2513 Colored Sticks (并查集+trie)

 1 #include<set>
 2 #include<queue>
 3 #include<cstdio>
 4 #include<cstdlib>
 5 #include<cstring>
 6 #include<iostream>
 7 #include<algorithm>
 8 using namespace std;
 9 const int N = 250010;
10 #define For(i,n) for(int i=1;i<=n;i++)
11 #define For0(i,n) for(int i=0;i<n;i++)
12 #define Rep(i,l,r) for(int i=l;i<=r;i++)
13 
14 char s1[11],s2[11];
15 int n,in[N*30],fa[N*30],ans;
16 struct Trie{
17     int sz,ch[N*30][26],v[N*30],Loc[N*30];
18     Trie(){sz=1;}
19     int insert(char st[]){
20         int now=1;v[1]++;int len=strlen(st);
21         For0(i,len){
22             int id=st[i]-‘a‘;
23             if(!ch[now][id]) ch[now][id]=++sz;
24             v[now=ch[now][id]]++;
25         }
26         if(Loc[now]) return Loc[now];
27         else         return Loc[now]=++n;
28     }
29 }trie;
30 
31 int find(int i){
32     if(fa[i]==i) return i;
33     else         return fa[i]=find(fa[i]);
34 }
35 
36 int main(){
37     #ifndef ONLINE_JUDGE
38         freopen("trie.in","r",stdin);
39     #endif // ONLINE_JUDGE
40     For0(i,N*30) fa[i]=i;
41     while(scanf("%s %s",&s1,&s2)!=EOF){
42         int x=trie.insert(s1),y=trie.insert(s2);
43         in[x]++;in[y]++;
44         int fx=find(x),fy=find(y);
45         if(fx!=fy) fa[fx]=fy;
46     }
47     int checks=find(1);
48     Rep(i,2,n) if(find(i)!=checks){
49         puts("Impossible\n");
50         return 0;
51     }
52     For(i,n) {
53         in[i]=in[i]%2;
54         if(in[i]) ans++;
55     }
56     if(ans==1||ans>=3) puts("Impossible");
57     else               puts("Possible");
58     return 0;
59 }