Phone List - HDU 1671 Trie树

电话号码一致性检查

最新推荐文章于 2019-09-04 21:36:33 发布

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本文介绍了一个电话号码列表的一致性检查问题，确保任一号码不是其他号码的前缀。通过使用Trie树并结合排序和清理操作来解决该问题，避免了错误匹配和超时问题。

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

Sample Output

NO
YES

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);
  }
}