Given a singly linked list, return a random node's value from the linked list. Each node must have the same probability of being chosen.
Follow up:
- What if the linked list is extremely large and its length is unknown to you?
- Could you solve this efficiently without using extra space?
Example:
// Init a singly linked list [1,2,3].
ListNode head = new ListNode(1);
head.next = new ListNode(2);
head.next.next = new ListNode(3);
Solution solution = new Solution(head);
// getRandom() should return either 1, 2, or 3 randomly. Each element should have equal probability of returning.
solution.getRandom();
见程序注释
运气好
