#ifndef Edge_
#define Edge_
//用于尋找深度優(yōu)先生成樹函數(shù)
class Edge
{
	friend ostream& operator<<(ostream&, Edge);
	friend class Undirected;
	friend void main(void);
private:
	int u, v;  //邊的端點
};

ostream& operator<<(ostream& out, Edge x)
   {out << x.u << ' ' << x.v; return out;}

#endif