hdu 1116 Play on Words

http://acm.hdu.edu.cn/showproblem.php?pid=1116

欧拉通路和欧拉回路

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <algorithm>

 4 #define maxn 1000

 5 using namespace std;

 6 

 7 int f[maxn],in[maxn],ou[maxn],a[maxn];

 8 bool vis[maxn];

 9 int n;

10 char str[maxn];

11 

12 int find(int x)

13 {

14     if(x==f[x]) return x;

15     return f[x]=find(f[x]);

16 }

17 

18 void union1(int x,int y)

19 {

20     int fx=find(x);

21     int fy=find(y);

22     if(fx!=fy)

23     f[fx]=fy;

24 }

25 

26 void inti()

27 {

28     for(int i=0; i<26; i++)

29     f[i]=i;

30 }

31 

32 int main()

33 {

34     int t;

35     scanf("%d",&t);

36     while(t--)

37     {

38         scanf("%d",&n);

39         inti();

40         memset(in,0,sizeof(in));

41         memset(ou,0,sizeof(ou));

42         memset(vis,false,sizeof(vis));

43         for(int i=0; i<n; i++)

44         {

45             scanf("%s",str);

46             int k=strlen(str);

47             ou[str[0]-'a']++;

48             in[str[k-1]-'a']++;

49             vis[str[0]-'a']=true;

50             vis[str[k-1]-'a']=true;

51             union1(str[0]-'a',str[k-1]-'a');

52         }

53         int ans=0;

54         for(int i=0; i<26; i++)

55         {

56             if(vis[i]&&f[i]==i)

57               ans++;

58         }

59         if(ans>1)

60         {

61             printf("The door cannot be opened.\n");

62             continue;

63         }

64         int m1=0,m2=0;

65         bool flag=true;

66         for(int j=0; j<26; j++)

67         {

68             if(vis[j]&&in[j]!=ou[j])

69             {

70                 if(in[j]-ou[j]==1)

71                 {

72                     m1++;

73                 }

74                 else if(ou[j]-in[j]==1)

75                 {

76                     m2++;

77                 }

78                 else flag=false;

79             }

80         }

81         if(flag&&((m1==0&&m2==0)||(m1==1&&m2==1)))

82         printf("Ordering is possible.\n");

83         else

84         printf("The door cannot be opened.\n");

85     }

86     return 0;

87 }

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