Linked List Cycle

Desicription

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

Follow up:

Can you solve it without using extra space?

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
/**
* 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) {
while(head) {
if(head->val == INT_MIN)
return true;
head->val = INT_MIN;
head = head->next;
}
return false;
}
};