HDU - 1671 Phone List

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
struct Node {
    int next[10];
    int num;
} node[100005];
int len = 0;
bool add(string& s) {
    int p = 0;
    bool f = false;
    for(int i = 0; i < s.size(); i++) {
        if(node[p].next[s[i] - '0'] == -1) {
            node[p].next[s[i] - '0'] = ++len;
            memset(node[len].next, -1, sizeof node[len].next);
            node[len].num = 0;
            p = len;
            f = true;
        }
        else {
            p = node[p].next[s[i] - '0'];
            if(node[p].num > 0) return false;
        }
    }
    node[p].num++;
    return f;
}
int main() {
    int T;
    cin >> T;
    while(T--) {
        len = 0;
        memset(node[0].next, -1, sizeof node[0].next);
        node[0].num = 0;
        int n;
        cin >> n;
        string s;
        bool f = true;
        for(int i = 1; i <= n; i++) {
            cin >> s;
            if(f) f = add(s);
        }
        if(f) cout << "YES" << endl;
        else cout << "NO" << endl;
    }
    return 0;
}