Algoritmul lui Lee

#include <iostream>
#include <fstream>
#include <iomanip>
#include <queue>
using namespace std;

struct Punct
{
    int coordX, coordY;
}start;

queue <pair<int, int>> coada;

const int di[] = { -1, 0, 1, 0 };
const int dj[] = { 0, 1, 0, -1 };

void Citire(int drumuri[][20], int& nrLinii, int& nrColoane, int& nrObstacole)
{
    ifstream fin("alee.in");

    fin >> nrLinii >> nrColoane >> nrObstacole;

    for (int i = 0; i < nrObstacole; i++)
    {
        Punct obstacol = { 0 };
        fin >> obstacol.coordX >> obstacol.coordY;
        drumuri[obstacol.coordX][obstacol.coordY] = -1;
    }

    fin >> start.coordX >> start.coordY;
    drumuri[start.coordX][start.coordY] = 0;
}

bool verif(Punct urmator, int nrLinii, int nrColoane)
{
    if (urmator.coordX < 0 || urmator.coordY < 0 || urmator.coordX >= nrLinii || urmator.coordY >= nrColoane)
        return false;
    return true;
}

void Lee(int drumuri[][20], int nrLinii, int nrColoane)
{
    Punct curent = { 0 }, urmator = { 0 };
    coada.push(make_pair(start.coordX, start.coordY));

    while (!coada.empty())
    {
        curent.coordX = coada.front().first;
        curent.coordY = coada.front().second;

        for (int dir = 0; dir < 4; dir++)
        {
            urmator.coordX = curent.coordX + di[dir];
            urmator.coordY = curent.coordY + dj[dir];
            if (verif(urmator, nrLinii, nrColoane) && drumuri[urmator.coordX][urmator.coordY] == 0)
            {
                drumuri[urmator.coordX][urmator.coordY] = drumuri[curent.coordX][curent.coordY] + 1;
                coada.push(make_pair(urmator.coordX, urmator.coordY));
            }
        }
        coada.pop();
    }
    drumuri[start.coordX][start.coordY] = 0;
    return;
}

void Afisare(int drumuri[][20], int nrLinii, int nrColoane)
{
    for (int i = 0; i < nrLinii; i++, cout << endl)
        for (int j = 0; j < nrColoane; j++)
            cout << setw(4) << drumuri[i][j];
}

int main()
{
    int drumuri[20][20] = { 0 }, nrLinii, nrColoane, nrObstacole;
    Citire(drumuri, nrLinii, nrColoane, nrObstacole);
    Lee(drumuri, nrLinii, nrColoane);
    Afisare(drumuri, nrLinii, nrColoane);

    return 0;
}