Construirea matricei de adiacenta si a drumurilor (rw)

#include <iostream>
using namespace std;

int n, m, a[100][100], i, j, k;

void citire()
{
    int x, y;
    cin >> n >> m;
    for(i = 1; i <= m; i++)
    {
        cin >> x >> y;
        a[x][y] = a[y][x] = 1;
    }
}

void rw()
{
    int i, j, k;
    for(k = 1; k <= n; k++)
        for(i = 1; i <= n; i++)
            for(j = 1; j <= n; j++)
                if(i != j)
                    if(a[i][j] == 0)
                        a[i][j] = a[i][k] * a[k][j];
 }

void afisare()
{
    for(i = 1; i <= n; i++) {
        for(j = 1; j <= n; j++)
            cout << a[i][j] << ' ';
        cout << endl;
    }
}

int main()
{
    citire();
    afisare();
    rw();
    afisare();
}