摘要： Given a linked list, return the node where the cycle begins. If there is no cycle, return null. Note: Do not modify the linked list. Follow up:Can you 阅读全文

摘要： Given a linked list, determine if it has a cycle in it. Follow up:Can you solve it without using extra space? 经典问题，判断一个单向链表是否有环，快慢指针，有相遇即有环。 阅读全文