Create Linked_List_Cycle.cc

Author: iphkwan

Linked_List_Cycle.cc

@@ -0,0 +1,23 @@
+/**
+ * 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) {
+        // IMPORTANT: Please reset any member data you declared, as
+        // the same Solution instance will be reused for each test case.
+        ListNode *fast = head, *slow = head;
+        while (fast && fast->next) {
+            fast = fast->next->next;
+            slow = slow->next;
+            if (fast == slow)
+                return true;
+        }
+        return false;
+    }
+};