HDU 1181 变形课（BFS）

题目链接

裸BFS，不复杂。

 1 #include <stdio.h>

 2 #include <stdlib.h>

 3 #include <string.h>

 4 int p[27][27],o[27],key[27];

 5 int main()

 6 {

 7     int i,j,len,end,start,a,z;

 8     char str[1000];

 9     while(scanf("%s",str)!=EOF)

10     {

11         z = 0;

12         memset(p,0,sizeof(p));

13         memset(o,0,sizeof(o));

14         len = strlen(str);

15         p[str[0]-'a'+1][str[len-1]-'a'+1] = 1;

16         for(;;)

17         {

18             scanf("%s",str);

19             if(str[0] == '0')

20             break;

21             len = strlen(str);

22             p[str[0]-'a'+1][str[len-1]-'a'+1] = 1;

23         }

24         start = end = 1;

25         key[1] = 2;

26         while(start <= end)

27         {

28             j = 1;

29             for(i = start;i <= end;i ++)

30             {

31                 if(o[key[i]] == 0)

32                 {

33                     for(a = 1;a <= 26;a ++)

34                     {

35                         if(p[key[i]][a] && !o[a])

36                         {

37                             key[end+j] = a;

38                             j ++;

39                         }

40                     }

41                     o[key[i]] = 1;

42                 }

43             }

44             start = end + 1;

45             end = end + j - 1;

46         }

47         if(o[13]) z = 1;

48         if(z)

49         printf("Yes.\n");

50         else

51         printf("No.\n");

52     }

53     return 0;

54 }