POJ2513 【并查集+欧拉路径+trie树】

 1 #include<stdio.h>
 2 #include<string.h>
 3 #define mem(a, b) memset(a, b, sizeof(a))
 4 const int MAXN = 250000 * 2 + 10;//最多MAXN种颜色 即最多MAXN种不同的点 
 5 
 6 char s1[12], s2[12];
 7 int deg[MAXN];
 8 int trie[MAXN][27], cnt, tot;
 9 int id[MAXN], pre[MAXN];
10 
11 int insert(char s[12])
12 {
13     int flag = 1;
14     int len = strlen(s);
15     int root = 0;
16     for(int i = 0; i < len; i ++)
17     {
18         int id = s[i] - ‘a‘;
19         if(!trie[root][id])
20         {
21             flag = 0;  //单词之前没出现过 
22             trie[root][id] = ++ cnt;
23         }
24         root = trie[root][id];
25     }
26     if(!flag)
27     {
28         tot ++;
29         id[root] = tot;
30         return id[root];
31     }
32     else
33         return id[root];
34 }
35 
36 int find(int x)
37 {
38     if(pre[x] == x)
39         return x;
40     else
41     {
42         int root = find(pre[x]);
43         pre[x] = root;
44         return pre[x];
45     }
46 }
47 
48 int main()
49 {
50     for(int i = 1; i <= MAXN + 1; i ++)
51         pre[i] = i;
52     while(scanf("%s%s", s1, s2) != EOF)
53     {
54         int a = insert(s1), b = insert(s2);//返回的是颜色所对应的序号
55         deg[a] ++, deg[b] ++; //点的度数 判断是否存在欧拉路径 
56         int x = find(a), y = find(b); //查找根节点 
57         if(x != y)
58             pre[y] = x;
59     }
60     int flag = 1;
61     for(int i = 1; i < tot; i ++) //总共有tot个不同的点 
62         if(find(i) != find(i + 1))
63         {
64             flag = 0;
65             break;
66         }
67     if(flag == 0)
68         printf("Impossible\n");
69     else
70     {
71         int xx = 0;
72         for(int i = 1; i <= tot; i ++)
73             if(deg[i] % 2)
74                 xx ++;
75         if(xx == 0 || xx == 2)
76             printf("Possible\n");
77         else
78             printf("Impossible\n");
79     }
80     return 0;
81 }