题解 | #链表中环的入口结点#
链表中环的入口结点
http://www.nowcoder.com/practice/253d2c59ec3e4bc68da16833f79a38e4
public ListNode aa(ListNode pHead) {
if (pHead == null || pHead.next == null) {
return null;
}
HashSet<ListNode> set = new HashSet();
while (pHead != null) {
if (!set.add(pHead)) {
return pHead;
}
pHead = pHead.next;
}
return null;
}