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
/* struct ListNode { int val; struct ListNode next; ListNode(int x) : val(x), next(NULL) { } }; / class Solution { public: ListNode EntryNodeOfLoop(ListNode pHead) { ListNode*p=pHead; while(p&&p->val>0) { p->val=0-p->val; //如果当前节点值大于0,则说明当前节点未被访问,并将其置为负值 p=p->next; } if(p==NULL) return NULL; else { p->val=-p->val; return p; } } };