题解 | #链表中环的入口结点#
链表中环的入口结点
https://www.nowcoder.com/practice/253d2c59ec3e4bc68da16833f79a38e4
空间复杂度O(1)解
class Solution {
public:
ListNode* EntryNodeOfLoop(ListNode* head) {
ListNode* l1 = head;
while (l1) {
if (l1->val < 0) {
l1->val *= -1;
return l1;
}
l1->val *= -1;
l1 = l1->next;
}
return NULL;
}
};
