Equivalent Suffix Tries - Test case generator

#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <map>

using namespace std;

// Tree isomorphism
map< vector<int> , int > M;
string S;
int cont;

int hash(int l, int r){
    vector<int> v;
    v.push_back(0);

    int aux = 0;

    for(int i = l,x = l;i <= r;++i){
        if(S[i] == '0') ++aux;
        else --aux;

        if(aux == 0){
            v.push_back(hash(x + 1,i - 1));
            x = i + 1;
        }
    }

    if(v.size() > 1) sort(v.begin() + 1,v.end());
    v.push_back(1);

    if(M.find(v) == M.end()) M[v] = cont++;

    return M[v];
}


// Trie
int next[10000][10],cont2;

void add(string s){
    int L = s.size();
    int pos = 0;

    for(int i = 0;i < L;++i){
        if(next[pos][ s[i] - 'a' ] == -1)
            next[pos][ s[i] - 'a' ] = cont2++;

        pos = next[pos][ s[i] - 'a' ];
    }
}

int B,L;

// Trie into string
string dfs(int pos){
    string ret = "0";

    for(int i = 0;i < B;++i){
        if(next[pos][i] != -1){
            ret += "0";
            ret += dfs(next[pos][i]);
            ret += "1";
        }
    }

    ret += "1";

    return ret;
}

int main(){
    //B : numer of different characters
    //L : length of the strings
    cin >> B >> L;

    string s;
    cont = 2;

    vector<string> v;
    v.push_back("");

    for(int i = 0;i < L;++i){
        int L2 = v.size();

        for(int j = 1;j < B;++j)
            for(int k = 0;k < L2;++k)
                v.push_back(v[k]);

        for(int j = 0,k = 0;j < B;++j)
            for(int x = 0;x < L2;++x)
                v[k++] += (char)('a' + j);
    }

    vector< pair<int,string> > H;

    bool have[26];

    for(int i = 0;i < v.size();++i){
        string s = v[i];

        memset(have,false,sizeof have);
        int alph = 0;
        bool ok = true;

        for(int j = 0;j < L;++j){
            if(!have[ s[j] - 'a' ]){
                if(s[j] - 'a' != alph) ok = false;
                have[ s[j] - 'a' ] = true;
                ++alph;
            }
        }

        if(alph < B || !ok) continue;

        memset(next,-1,sizeof next);
        cont2 = 1;

        string s2;

        for(int j = L - 1;j >= 0;--j){
            s2 = s[j] + s2;
            add(s2);
        }

        string ret = dfs(0);
        S = ret;
        int ret2 = hash(0,ret.size() - 1);
        H.push_back(make_pair(ret2,s));
    }

    sort(H.begin(),H.end());

    cout << H.size() << endl;

    for(int i = 0;i < H.size();){
        int e = i;

        while(e < H.size() && H[e].first == H[i].first) ++e;

        for(int j = i;j < e;++j)
            cout << H[j].second << " " << e - i << endl;


        i = e;
    }

    return 0;
}