Phone List - HDU 1671 Trie树

Phone List

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 10511    Accepted Submission(s): 3617

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

 

题意：不能让一个电话号码是另一个电话号码的前缀和。

思路：Trie树，注意排序和删除原树，不然会WA和TLE。

AC代码如下：

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;struct node{ char s[20];  int len;}number[10010];bool cmp(node a,node b){ return a.len<b.len;}bool flag;int T,t;struct Trie{ int index;  Trie *next[10];  Trie()  { index=-1;    memset(next,0,sizeof(next));  }};void Trie_Insert(Trie *tr,char *s){ if(!flag)   return;  if(*s!='\0')  { if(tr->next[*s-'0']==0)     tr->next[*s-'0']=new Trie;    if(tr->index==t)     flag=false;    Trie_Insert(tr->next[*s-'0'],s+1);  }  else   tr->index=t;}void Trie_clear(Trie *tr){ if(tr==0)   return;  for(int i=0;i<=9;i++)   Trie_clear(tr->next[i]);  delete tr;}int main(){ int n,i,j,k;  scanf("%d",&T);  for(t=1;t<=T;t++)  { scanf("%d",&n);    flag=true;    Trie *root=new Trie;    for(i=1;i<=n;i++)    { scanf("%s",number[i].s);      number[i].len=strlen(number[i].s);    }    sort(number+1,number+1+n,cmp);    for(i=1;i<=n;i++)     Trie_Insert(root,number[i].s);    if(flag)     printf("YES\n");    else     printf("NO\n");    Trie_clear(root);  }}