141 Linked List Cycle (to determine if a linked list has a ring medium)

The link list has loops, returns True, otherwise returns false

Ideas: Two pointers, a fast and slow, can meet the ring, for the empty ring

PS: Many lists of topics: You can use this idea

1 /**2 * Definition for singly-linked list.3 * struct ListNode {4 * int val;5 * ListNode *next;6 * ListNode (int x): Val (x), Next (NULL) {}7  * };8  */9 classSolution {Ten  Public: One     BOOLHascycle (ListNode *head) { A         if(Head==null)return false; -ListNode *p1,*P2; -P1=p2=head; the          while(p2->next&&p2->next->next) {//To determine if the P->next->next is empty first to determine whether the p->next is empty, so as not to produce p->next->next not exist in the egg pain problem -P1=p1->Next; -P2=p2->next->Next; -             if(p1==p2) +                 return true; -         } +         return false; A     } at};

141 Linked List Cycle (to determine if a linked list has a ring medium)