試題詳解

19. Given the head of a linked list, determine whether the linked list has a cycle. If it does have a cycle, return true; otherwise, return false. The example and algorithm are shown below.

Which of the followings should be "Q1" and "Q2" in the algorithm?
(A) Q1: a = a -＞ next; Q2: b = b -＞ next;
(B) Q1: a = b; Q2: b = b -＞ next;
(C) Q1: a = a -＞ next; Q2: b = b -＞ next;
(D) Q1: a = a -＞ next -＞ next; Q2: b = b -＞ next;
(E) Q1: a = a -＞ next; Q2: b = b -＞ next -＞ next;