ADN - not finished

#include <bits/stdc++.h>

using namespace std;

ifstream fin("adn.in");
ofstream fout("adn.out");

vector<int> preffix_function(const string &A) {
    vector<int> pi(A.size());
    int N = A.size() - 1;
    for(int i = 2, q = 0; i <= N; ++i) {
        while(q && A[q + 1] != A[i])
            q = pi[q];
        if(A[q + 1] == A[i])
            ++q;
        pi[i] = q;
    }
    return pi;
}

vector<int> pref;

bool found(const string &A, const string &B) {
    int N = B.size() - 1, M = A.size() - 1;
    for(int i = 1, q = 0; i <= N; ++i) {
        while(q && A[q + 1] != B[i])
            q = pref[q];
        if(A[q + 1] == B[i])
            ++q;
        if(q == M)
            return true;
    }
    return false;
}

int main() {
    int N;
    fin >> N;
    vector<string> a(N), new_a;
    for(string &s : a) {
        fin >> s;
        s = ' ' + s;
    }
    for(int i = 0; i < N; ++i) {
        pref.clear();
        pref = preffix_function(a[i]);
        bool ap = false;
        for(int j = 0; j < N && !ap; ++j)
            if(i != j && a[j].size() >= a[i].size() && found(a[i], a[j]))
                ap = true;
        if(!ap)
            new_a.push_back(a[i]);
    }
    a = new_a;

}