https://leetcode.com/problems/linked-list-cycle/

리스트가 순환 하는지 여부를 return 하라. 앞서 풀었던 fast, slow node를 이용한다.

class Solution {
 public:
	 bool hasCycle(ListNode *head) {
		 ListNode* fastNode = head;
		 ListNode* slowNode = head;
		 
		 while (fastNode && fastNode->next)
		 {
			 fastNode = fastNode->next->next;
			 slowNode = slowNode->next;

			 if (fastNode == slowNode)
			 {
				 return true;
			 }
		 }
		 return false;
	 }
 };

Runtime: 16 ms, faster than 23.36% of C++ online submissions for Linked List Cycle.

Memory Usage: 8 MB, less than 21.89% of C++ online submissions for Linked List Cycle.