Phone Number(字典树)

【Description
Description】
We know that if a phone number A is another phone number B’s prefix, B is not able to
be called. For an example, A is 123 while B is 12345, after pressing 123, we call A, and not
able to call B.
Given N phone numbers, your task is to find whether there exits two numbers A and B
that A is B’s prefix.
Input
【Input
Input】
The input consists of several test cases.
The first line of input in each test case contains one integer N (0<N<1001), represent the
number of phone numbers.
The next line contains N integers, describing the phone numbers.
The last case is followed by a line containing one zero.
Output
【Output
Output】
For each test case, if there exits a phone number that cannot be called, print “NO”,
otherwise print “YES” instead.
Sample Input】
【Sample Input
2
012
012345
2
12
012345
0
Sample Output】
【Sample Output
NO
YES

 1 #include<stdio.h>

 2 #include<stdlib.h>

 3 struct node

 4 {

 5     int flag;

 6     struct node *next[10];

 7 }*root;

 8 int tag;

 9 struct node *creat()

10 {

11     struct node *p;

12     p=(struct node *)malloc(sizeof(struct node));

13     p->flag=0;

14     for(int i=0;i<10;i++)

15         p->next[i]=NULL;

16      return p;

17 }

18 void inser(char *s)

19 {

20     int i;

21     struct node *p;

22     p=root;

23     for(i=0;s[i]!='\0';i++)

24     {

25         if(!(p->next[s[i]-'0'])) p->next[s[i]-'0']=creat();

26         p=p->next[s[i]-'0'];

27         if(p->flag==1) tag=1;判断p节点是否是某字符串的结束。

28     }

29     p->flag=1;

30 }

31 int main ()

32 {

33     int t;

34     char s[1010];

35     while(~scanf("%d",&t))

36     {

37         if(!t) break;

38         root=creat();

39         tag=0;

40         while(t--)

41         {

42             scanf("%s",s);

43             inser(s);

44         }

45         if(tag==1)

46                 printf("NO\n");

47         else printf("YES\n");

48     }

49     return 0;

50 }