phone list

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <cstdlib>
#include <istream>

#define MAX 10

struct Trie {
    Trie *next[MAX];
    int v;
};

Trie *root;

void creattrie(char *str)
{
    int i, j, len, t;
    Trie *p, *q;
    
    p = root;
    len = strlen(str);
    
    for (i = 0; i < len; i++) {
        t = str[i] - '0';
        if (p->next[t] == NULL) {
            q = new Trie;
            q->v = 1;
            for (j = 0; j < MAX; j++)
                q->next[j] = NULL;
            p->next[t] = q;
            p = p->next[t];
        }
        else {
            p->next[t]->v++;
            p = p->next[t];
        }
    }
    p->v = -1;
}

int find(char *str)
{
    Trie *p;
    p = root;
    int i, j, len, t;
    len = strlen(str);
    
    for (i = 0; i < len; i++) {
        t = str[i] - '0';
        p = p->next[t];
        if (p == NULL)
            return 0;
        if (p->v == -1)
        return -1;
    }
 return -1;
}

int del(Trie* l )
{
    
    int i;
    
    if (l == NULL)
        return 0;
    for (i = 0; i < MAX; i++) {
        if(l->next[i] != NULL)
            del(l->next[i]);
    }
    free(l);
    return 0;
}
       
int main( )
{   
    int i, j, T, M, flag;
    char str[20];
    scanf("%d", &T);
    while (T--) {
        root = new Trie;
        for (i = 0; i < MAX; i++)
             root->next[i] = NULL;
        flag = 0;
        scanf("%d",&M);
        for (i = 0; i < M; i++) {
           scanf("%s",str);
           if (find(str)==-1)
             flag = 1;
           if (flag)
             continue;
           creattrie(str);
        }
        if (flag)
             printf("NO\n");   
         else 
             printf("YES\n");
        del(root);
    }
        return 0;
}