并查集

class UnionSet
{
public:
UnionSet(size_t size)
:_size(size)
{
_unionset.resize(size, -1);
}

void Combine(size_t pos1, size_t pos2)     //合并函数
{
int root1 = FindAncestor(pos1);
int root2 = FindAncestor(pos2);
_unionset[root1] += _unionset[root2];
_unionset[root2] = root1;
}

int FindAncestor(size_t pos)     //寻找祖先节点的函数
{
while (_unionset[pos] >= 0)  //当某一元素为负数时说明，到了该集合的根节点了
{
pos = _unionset[pos];
}
return pos;
}

protected:
vector<int> _unionset;
size_t _size;
};