并查集

int find(int x)
{
    int r = x;
    while(father[r] != r)
        r = father[r];
    return r;
}

int find(int x)
{
    if(father[x] != x)
        father[x] = find(father[x]);
    return father[x];

}

int find(int x)
{
    int i, j, r = x;
    while(father[r] != r)
        r = father[r];
    i = x;
    while(i != r)
    {
        j = father[i];
        father[i] = r;
        i = j;
    }
    return r;
}