linkedListCycle.java

/**
 * Definition for singly-linked list.
 * class ListNode {
 * int val;
 * ListNode next;
 * ListNode(int x) {
 * val = x;
 * next = null;
 * }
 * }
 */
public class Solution {
 public boolean hasCycle(ListNode head) {
 public boolean hasCycle(ListNode head) {
 ListNode fast_iter = head;
 ListNode slow_iter = head;
 while (fast_iter!=null && fast_iter.next!=null) {
 slow_iter = slow_iter.next;
 fast_iter = fast_iter.next.next;
 if (fast_iter==slow_iter) {
 return true;
 }
 }
 return false;
 }
 }
}