hdu 1671(字典树)

/*
*  字典树 
*/
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <iostream>

using namespace std;

const int N = 11;

bool yes;
char str[N];
struct node {
    bool flag;
    node *child[10];
    node() {
        flag = false;
        for (int i=0; i<10; ++i) child[i] = NULL;
    }
}*root;

void insert(char str[]) {
    node *p = root;
    int len = strlen(str);
    for (int k,i=0; i<len; ++i, p=p->child[k]) {
        k = str[i] - '0';
        if (!p->child[k]) p->child[k] = new node();
        else if (i == len-1) {yes = false; return;}
        if (p->child[k]->flag) {yes = false; return;}
    }
    p->flag = true;
}

void del(node *p) {//释放内存 
    for (int i=0; i<10; ++i) {
        if (p->child[i]) del(p->child[i]);
    }
    delete p;
    p = NULL;
}

int main() {
    int t;
    scanf ("%d", &t);
    while (t--) {
        int n;
        scanf ("%d", &n);
        yes = true;
        root = new node();
        while (n--) {
            scanf ("%s", str);
            if (yes) insert(str);
        }
        if (yes) puts("YES");
        else puts("NO");
        del(root);
    }
    return 0;
}