Phone number - Multiway Trees

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本文介绍了一个算法，用于检查电话号码列表是否具有一致性，即确保任一号码都不是另一个号码的前缀。通过构建特殊的数据结构来高效地完成这一任务。

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Phone number

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:
Emergency 911
Alice 97625999
Bob 91125426

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 ≤ 160, 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

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

// Problem#: 17148
// Submission#: 4378675
// The source code is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License
// URI: http://creativecommons.org/licenses/by-nc-sa/3.0/
// All Copyright reserved by Informatic Lab of Sun Yat-sen University
#include <cstdio>
#include <cstring>
#include <iostream>

struct Node{
    bool end ;
    Node *index [10] ;
};
typedef Node* Nodeptr ;

Node Memory[100010] ;
int range = 0 ; bool  ans = 0 ; char str[13] ;Nodeptr head = NULL ;

Nodeptr getnew()
{
    Nodeptr p = &Memory[range++] ;
    p->end = 0 ; 
    for(int i=0;i<10;i++)
    {
        p -> index[i] = NULL;
    }
    return p ;
}

void insert(){
    if(ans) return;
    Nodeptr *tra =  &head ;
    int deep = 0 ;
    for (;str[deep]; ++deep)
    {
        if((*tra) == NULL){
            (*tra) = getnew() ;
        }
        else{
            if((*tra)->end == 1){
                ans = 1 ; return ;
            }
        }
        (tra) = &(*tra)->index[(int)(str[deep] - '0')] ;
    }

    if( (*tra) != NULL )
    {
        ans = 1 ;
        return ;
    }   
    (*tra) = getnew();
    (*tra) -> end = 1 ;    
}

int main (){
    int test_case = 0 ; scanf("%d" , &test_case) ;
    while(test_case -- > 0 ){
        ans = 0 ; range = 0 ;
        int input = 0 ; scanf("%d" , &input) ;
        while(input --){
            scanf("%s" , str) ;
            insert() ;
        }
        if(!ans) puts("YES");
        else puts("NO");
        head = NULL ;
    }
    return 0;
}