LeetCode Q141: Linked List Cycle

Given a linked list, determine if it has a cycle in it.

Follow up:
Can you solve it without using extra space?

	/**
	* Definition for singly-linked list.
	* struct ListNode {
	* int val;
	* ListNode *next;
	* ListNode(int x) : val(x), next(NULL) {}
	* };
	*/
	class Solution {
	public:
	bool hasCycle(ListNode *head) {
	if(head==NULL)
	return false;
	ListNode* p0 = head;
	ListNode* p1 = head;
	while(p1->next!=NULL&&p1->next->next!=NULL){
	p0 = p0->next;
	p1 = p1->next->next;
	if(p0==p1)
	return true;
	}
	return false;
	}
	};

view raw Q141LinkListCycle.cpp hosted with ❤ by GitHub