不想写Trie（或Hash）的往这看

sort+string::find函数

#include <iostream>
#include <string>
#include <cstdio>
#include <algorithm>
using namespace std;

int n;
const int N = 10000 + 20;
string a[N];

int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        cin >> n;
        for (int i = 1; i <= n; i++)
        {
            cin >> a[i];
        }
        sort(a + 1, a + 1 + n);
        bool flag = false;
        for (int i = 1; i <= n - 1; i++)
        {
            if (a[i + 1].find(a[i]) == 0)
            {
                flag = true;
                break;
            }
        }
        if (flag)
        {
            cout << "NO" << endl;
        }
        else
        {
            cout << "YES" << endl;
        }
    }
}