detect loop in LL

Author: accodes21

flyodDetectLoop.cpp

@@ -0,0 +1,34 @@
+/**
+ * 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* fast = head;
+        ListNode* slow = head;
+
+        while(fast != NULL && fast->next != NULL){
+            fast = fast->next;
+
+            if(fast != NULL){
+                fast = fast->next;
+            }
+
+            slow = slow->next;
+
+            if(slow == fast){
+                return true;
+            }
+        }
+        return false;
+    }
+};