Add LinkedListCycle.java

Author: tinycedar

LinkedListCycle.java

@@ -0,0 +1,36 @@
+/**
+ * 
+ */
+package leetcode;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * @author hzlinqien
+ *
+ */
+
+public class LinkedListCycle {
+
+	public boolean hasCycle(ListNode head) {
+		Set<ListNode> nodeMap = new HashSet<>();
+		for (ListNode temp = head; temp != null; temp = temp.next) {
+			if (nodeMap.contains(temp)) {
+				return true;
+			}
+			nodeMap.add(temp);
+		}
+		return false;
+	}
+
+	class ListNode {
+		int val;
+		ListNode next;
+
+		ListNode(int x) {
+			val = x;
+			next = null;
+		}
+	}
+}