Phone List

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Problem Description

Given a list of phone numbers, determine if it is consistent in the sense that no number is the prefix of another. Let’s say the phone catalogue listed these numbers:
1. Emergency 911
2. Alice 97 625 999
3. Bob 91 12 54 26
In this case, it’s not possible to call Bob, because the central would direct your call to the emergency line as soon as you had dialled the first three digits of Bob’s phone number. So this list would not be consistent.

Input

The first line of input gives a single integer, 1 <= t <= 40, the number of test cases. Each test case starts with n, the number of phone numbers, on a separate line, 1 <= n <= 10000. Then follows n lines with one unique phone number on each line. A phone number is a sequence of at most ten digits.

Output

For each test case, output “YES” if the list is consistent, or “NO” otherwise.

Sample Input

2391197625999911254265113123401234401234598346

Sample Output

NOYES

Source

2008 “Insigma International Cup” Zhejiang Collegiate Programming Contest - Warm Up（3）

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此题主要还是关于Trie树的应用

#include<stdio.h>#include<stdlib.h>#define MAX 10typedef struct PhoneNode{    enum{true,false} isStr;//标记该节点为电话结尾    struct PhoneNode *next[MAX];}Phone;char flag=0;//0:表明Yes   1:表明No//将新号码插入至字典树//插入过程还需判断是否插入的号码中带有结尾标记//以及指向的下一个节点是否都是为空void insert(Phone *root,const char *s){    int i;    Phone *p=root;    Phone *temp;    while(*s!='\0')    {        if(p->next[*s-'0']==NULL)//如果不存在，则建立节点        {            temp=(Phone *)malloc(sizeof(Phone));            for(i=0;i<MAX;i++)            {                temp->next[i]=NULL;            }            temp->isStr=false;            p->next[*s-'0']=temp;        }        if(p->isStr==true)            flag=1;        p=p->next[*s-'0'];        s++;    }    p->isStr=true;//号码结束的地方标记此处可以构成一个电话    for(i=0;i<MAX;i++)    {        if(p->next[i]!=NULL)        {            flag=1;            break;        }    }}void del(Phone *root){    int i;    for(i=0;i<MAX;i++)    {        if(root->next[i]!=NULL)        {            del(root->next[i]);        }    }    free(root);}int main(void){   int t,n;//t为测试的例子 n为该组测试的号码数   int i,j,k;   char s[100];   Phone *root=(Phone *)malloc(sizeof(Phone));    for(i=0;i<MAX;i++)    {        root->next[i]=NULL;    }    root->isStr=false;   scanf("%d\n",&t);   for(j=0;j<t;j++)   {      scanf("%d\n",&n);      for(k=0;k<n;k++)      {        scanf("%s",s);        insert(root,s);      }      if(flag==0)        printf("YES\n");      else printf("NO\n");      del(root);//释放空间        root=(Phone *)malloc(sizeof(Phone));        for(i=0;i<MAX;i++)        {            root->next[i]=NULL;        }        root->isStr=false;      flag=0;   }   del(root);//释放空间   return 0;}

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