Lowest common ancestor

bool adj[9][9];
bool visit[9];
int lca[9][9];

int find(int x)
{
    return x == p[x] ? x : (p[x] = find(p[x]));
}

int DFS(int x)
{
    if (visit[x]) return;
    visit[x] = true;

    for (int y=0; y<9; ++y)
        if (visit[y])
            lca[x][y] = lca[y][x] = find(y);

    // DFS
    for (int y=0; y<9; ++y)
        if (adj[x][y])
        {
            DFS(y);
            p[y] = x;
        }
}
void demo()
{
    for (int i=0; i<9; ++i) p[i] = i;

    for (int i=0; i<9; ++i) visit[i] = false;
    DFS(0);

    int x, y;
    while (cin >> x >> y)
        cout << "" << lca[x][y];
}