NO4——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)
    return x;
    else
    return father[x] =find(father[x]);
}
*/

void join(int x,int j)
{
    int fx = find(x),fy = find(y);
    if(fx!=fy)
    father[fx] = fy;
}

void Union(int x,int y)
{
    int rx,ry;
    rx = find(x);
    ry = find(y);
    father[rx] = ry;
}