poj 2513 欧拉图/trie

 1 #include<iostream>
 2 #include<cstring>
 3 #include<cstdio>
 4 #include<map>
 5 using namespace std;
 6 int N;
 7 struct node
 8 {
 9     node *next[26];
10     int v;
11     node(){v=0;memset(next,NULL,sizeof(next));}
12 }*root;
13 int gec(char *s)
14 {
15     int len=strlen(s);
16     node *p=root;
17     for(int i=0;i<len;++i)
18     {
19         if(p->next[s[i]-‘a‘]==NULL) p->next[s[i]-‘a‘]=new node();
20         p=p->next[s[i]-‘a‘];
21     }
22     if(p->v==0) p->v=++N;
23     return p->v;
24 }
25 int cnt[500005];
26 int f[500005];
27 int getf(int v){return f[v]==v?v:f[v]=getf(f[v]);}
28 int main()
29 {
30     char s1[15],s2[15];
31     int i;
32     for(i=1;i<=500000;++i)f[i]=i;
33     root=new node();
34     while(scanf("%s%s",s1,s2)!=EOF){
35         int u=gec(s1);
36         int v=gec(s2);
37         int fu=getf(u),fv=getf(v);
38         if(fu!=fv) f[fv]=fu;
39         cnt[u]++;
40         cnt[v]++;
41     }
42     int s=0,x=0;
43     for(i=1;i<=N;++i)
44     {
45         if(cnt[i]%2==1) s++;
46         if(i==getf(i))x++;
47     }
48     if(x<=1&&(s==0||s==2)) puts("Possible");
49     else puts("Impossible");
50     return 0;
51 }