Rayuela literaria

#include <iostream>
#include <fstream>
#include <vector>
#include <map>

#define a1 (a+x[i])
#define b1 (b+y[i])

using namespace std;

int x[] = {1, 0, -1, 0};
int y[] = {0, 1, 0, -1};

struct Grafo
{
    vector <vector <int> > adj;
    vector <vector <char> > letra;
    int tam, cant;

    bool valido(int a, int b)
    {
        return (0 <= a && a < tam && 0 <= b && b < tam);
    }

    int maximo;

    string s;

    void floodfill(int a, int b, int pos, int puntaje)
    {
        if(pos == s.size())
        {
            maximo = max(maximo, puntaje);
            return;
        }

        for(int i=0; i<4; i++)
            if(valido(a1, b1) && letra[a1][b1] == s[pos])
                floodfill(a1, b1, pos+1, puntaje+adj[a1][b1]);
    }

    void leer(istream &in, ostream &out)
    {
        in >> tam >> cant;
        adj = vector <vector <int> > (tam, vector <int> (tam));
        letra = vector <vector <char> > (tam, vector <char> (tam));

        vector <vector <pair<int, int> > > inicios(300);

        for(int i=0; i<tam; i++)
        {
            for(int j=0; j<tam; j++)
            {
                in >> letra[i][j] >> adj[i][j];
                inicios[letra[i][j]].push_back(make_pair(i, j));
            }
        }

        for(int i=0; i<cant; i++)
        {
            in >> s;

            maximo = 0;
            for(int j=0; j<inicios[s[0]].size(); j++)
            {
                int pos = 1;
                int px = inicios[s[0]][j].first;
                int py = inicios[s[0]][j].second;
                int val = adj[px][py];

                floodfill(px, py, pos, val);
            }

            out << maximo << endl;
        }
    }
};

int main()
{
    Grafo g;
    g.leer(cin, cout);

    return 0;
}