Suppose we want to add an extra operation, deunion, which undoes the last union operation that has not been already undone.

a. Show that if we do union-by-height and finds without path compression, then deunion is easy, and a sequence of M union, find, and deunion operations takes O(M logN) time.

b. Why does path compression make deunion hard?

c. Show how to implement all three operations so that the sequence of M operations takes O(M logN/log logN) time.

Please do not copy/paste, the answers on other posts are all the same. I need a different answer because the other answer is difficult for me to understand. Thanks!