..

include

include

include

include

using namespace std;

struct Node
{
int son[10];
bool end;
Node()
{
memset(son, -1, sizeof son);
end = false;
}
};

int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int T;
cin >> T;
while (T--)
{
vector trie;
trie.emplace_back(Node()); //根节点
int n;
cin >> n;
bool flag = true; //true代表合法，没有前缀关系

for (int i = 0; i < n; i++)
{
string s;
cin >> s;
if (!flag) continue; //已经发现非法，跳过插入

int p = 0;
for (char ch : s)
{
int c = ch - '0';
//情况1：走到中间，遇到某个旧单词结束 →旧串是当前串前缀
if (trie[p].end == true)
{
flag = false;
break;
}
if (trie[p].son[c] == -1)
{
trie.emplace_back(Node());
trie[p].son[c] = trie.size() - 1;
}
p = trie[p].son[c];
}
if (!flag) continue;

//情况2：插入完本串，该节点还有子节点 →本串是某个旧串前缀
for (int k = 0; k < 10; k++)
{
if (trie[p].son[k] != -1)
{
flag = false;
break;
}
}
trie[p].end = true;
}
if (flag)
cout << "YES\n";
else
cout << "NO\n";
}
return 0;
}