******** fig8.13 **********

	/* assumes root1 and root2 are roots */
	/* union is a C keyword, so this routine is named set_union */

	void
	set_union( DISJ_SET S, set_type root1, set_type root2 )
	{
		if( S[root2] < S[root1] )	/* root2 is deeper set */
			S[root1] = root2;	/* make root2 new root */
		else
		{
			if( S[root2] == S[root1] )	/* same height, so update */
				S[root1]--;
			S[root2] = root1;	/* make root1 new root */
		}
	}