linked_list_cycle

hitzzc · hitzzc · commit a8663b41002c · 2016-10-12T13:20:15.000+08:00
diff --git a/README.md b/README.md
@@ -123,7 +123,8 @@ Golang solution for leetcode. For each problem, there is a simple *_test.go to t
 #### [137. single number II](https://github.com/hitzzc/go-leetcode/tree/master/single_number_II)
 #### [138. copy_list_with_random_pointer](https://github.com/hitzzc/go-leetcode/tree/master/copy_list_with_random_pointer)
 #### [139. word break](https://github.com/hitzzc/go-leetcode/tree/master/word_break)
-#### [140. word break II](https://github.com/hitzzc/go-leetcode/tree/master/word_break II)
+#### [140. word break II](https://github.com/hitzzc/go-leetcode/tree/master/word_break_II)
+#### [141. Linked List Cycle](https://github.com/hitzzc/go-leetcode/tree/master/linked_list_cycle)
 
 
 
diff --git a/linked_list_cycle/linked_list_cycle.cpp b/linked_list_cycle/linked_list_cycle.cpp
@@ -0,0 +1,20 @@
+struct ListNode {
+	int val;
+	ListNode *next;
+	ListNode(int x) : val(x), next(NULL) {}
+};
+class Solution {
+public:
+	bool hasCycle(ListNode *head) {
+		ListNode* fast = head;
+		ListNode* slow = head;
+		bool first_step = true;
+		while (first_step || fast!=slow){
+			first_step = false;
+			for (int i = 0; i < 2 && fast!=NULL; ++i) fast = fast->next;
+			if (fast==NULL) return false;
+			slow = slow->next;
+		}
+		return true;
+	}
+};
