POJ 2513 Colored Sticks(字典树+无向图欧拉路）

题目链接

无向图啊。。。

  1 #include <stdio.h>
  2 #include <string.h>
  3 #include <stdlib.h>
  4 int o1[510401],o[510401],num;
  5 struct node
  6 {
  7     int flag;
  8     struct node *next[26];
  9 };
 10 struct node *build()
 11 {
 12     int i;
 13     struct node *p;
 14     p = (struct node *)malloc(sizeof(struct node));
 15     p -> flag = 0;
 16     for(i = 0;i <= 25;i ++)
 17     {
 18         p -> next[i] = NULL;
 19     }
 20     return p;
 21 }
 22 int insert(struct node *head,char *str)
 23 {
 24     int i;
 25     struct node *p;
 26     p = head;
 27     for(i = 0;str[i];i ++)
 28     {
 29         if(p -> next[str[i]-'a'] == NULL)
 30         p -> next[str[i] - 'a'] = build();
 31         p = p -> next[str[i]-'a'];
 32     }
 33     if(p -> flag == 0)
 34     {
 35         p -> flag = num;
 36         num ++;
 37         return p -> flag;
 38     }
 39     else
 40     return p->flag;
 41 }
 42 int find(int x)
 43 {
 44     int r,t;
 45     r = x;
 46     while(x != o[x])
 47     x = o[x];
 48     while(r != x)
 49     {
 50         t = o[r];
 51         o[r] = x;
 52         r = t;
 53     }
 54     return x;
 55 }
 56 void merge(int x,int y)
 57 {
 58     x = find(x);
 59     y = find(y);
 60     if(x != y)
 61         o[x] = y;
 62 }
 63 int main()
 64 {
 65     char str1[20],str2[20];
 66     int i,x,y,z,k,ru;
 67     struct node *head;
 68     head = build();
 69     num = 1;
 70     for(i = 1;i <= 510000;i ++)
 71     o[i] = i;
 72     while(scanf("%s%s",str1,str2)!=EOF)
 73     {
 74         x = insert(head,str1);
 75         o1[x] ++;
 76         y = insert(head,str2);
 77         o1[y] ++;
 78         merge(x,y);
 79     }
 80     z = 1;
 81     k = find(1);
 82     for(i = 1;i <= num-1;i ++)
 83     {
 84         if(find(i) != k)
 85         {
 86             z = 0;
 87             break;
 88         }
 89     }
 90     ru = 0;
 91     for(i = 1;i <= num-1&&z;i ++)
 92     {
 93        if(o1[i]%2)
 94        ru ++;
 95     }
 96     if(z&&ru == 2)
 97     printf("Possible\n");
 98     else if(z&&!ru)
 99     printf("Possible\n");
100     else
101     printf("Impossible\n");
102     return 0;
103 }
posted @ 2012-08-18 14:21  Naix_x  阅读(177)  评论(0)  编辑  收藏  举报