Operation Number of objects updated MAKE-SET(X1) MAKE-SET(X2) 1 : MAKE-SET(Xn) 1 Union操作对象 UNION(X2,X1) 1 的次序不影响结 UNION(X3,x2) 2 果，却影响效率 UNION(X4,X3) 3 这对你有什么启发？ : UNION(Xn,Xn-1) Figure 21.3 A sequence of 2n-1 operations on n objects that takes (n2)time,or (n)time per operation on average,using the linked-list set representation and the simple implementation of UNION.Union操作对象 的次序不影响结 果，却影响效率 这对你有什么启发？