poj 2513 Colored Sticks( 字典树哈希+ 欧拉回路 + 并查集)

题目：http://poj.org/problem?id=2513

参考博客：http://blog.csdn.net/lyy289065406/article/details/6647445

http://www.cnblogs.com/LK1994/p/3263462.html

 #include <iostream>
 #include<cstdio>
 #include<cstring>
 #include<cstdlib>
 #include<stack>
 #include<queue>
 #include<iomanip>
 #include<cmath>
 #include<map>
 #include<vector>
 #include<algorithm>
 #define N 500010
 using namespace std;

 int degree[N],bin[N],id = ;

 struct tree
 {
     int flag,id;
     struct tree* next[];
 }*root;
 struct tree* creat()
 {
     struct tree *p=(struct tree*)malloc(sizeof(struct tree));
     p->flag =;
     for(int i = ; i < ; i++)
         p->next[i] = NULL;
     return p;
 }

 int find(int x)
 {
     if(bin[x] != x)
         bin[x] = find(bin[x]);
     return bin[x];
 }

 int hash(char s[])
 {
     struct tree *p = root;
     for(int i = ; s[i]; i++)
     {
         if(p->next[s[i]-'a'] == NULL)
             p->next[s[i]-'a'] = creat();
         p = p->next[s[i]-'a'];
     }
     if(p->flag != )
     {
         p->flag = ;
         p->id = id++;
     }
     return p->id;
 }

 int check()
 {
     int sum = ;
     int x = find();
     for(int i = ; i < id; i++)
         if(find(i) != x)
             return ;
     for(int i = ; i < id; i++)
     {
         if(degree[i]%)
             sum++;
     }
     if(sum ==  || sum == )
         return ;
     return ;
 }

 int main()
 {
     int u,v,x,y;
     char s1[],s2[];
     memset(degree,,sizeof(degree));
     for(int i=; i<=; i++)
     bin[i]=i;
     root=creat();
     while(scanf("%s %s",s1,s2)!=EOF)
     {
         u =hash(s1);  v =hash(s2);
         degree[u]++;   degree[v]++;
         x=find(u);
         y=find(v);
         if(x!=y)
             bin[x]=y;
     }
     if(check()) printf("Possible\n");
     else printf("Impossible\n");
     return ;
 }